diff --git a/commonmark/src/main/java/org/commonmark/internal/DocumentParser.java b/commonmark/src/main/java/org/commonmark/internal/DocumentParser.java
index 9121d6d49..aeab876d4 100644
--- a/commonmark/src/main/java/org/commonmark/internal/DocumentParser.java
+++ b/commonmark/src/main/java/org/commonmark/internal/DocumentParser.java
@@ -1,5 +1,8 @@
 package org.commonmark.internal;
 
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.Reader;
 import org.commonmark.internal.util.Parsing;
 import org.commonmark.internal.util.Substring;
 import org.commonmark.node.*;
@@ -38,6 +41,7 @@ public class DocumentParser implements ParserState {
 
     private final List<BlockParserFactory> blockParserFactories;
     private final InlineParserImpl inlineParser;
+    private final DocumentBlockParser documentBlockParser;
 
     private List<BlockParser> activeBlockParsers = new ArrayList<>();
     private Set<BlockParser> allBlockParsers = new HashSet<>();
@@ -46,6 +50,9 @@ public class DocumentParser implements ParserState {
     public DocumentParser(List<BlockParserFactory> blockParserFactories, InlineParserImpl inlineParser) {
         this.blockParserFactories = blockParserFactories;
         this.inlineParser = inlineParser;
+        
+        this.documentBlockParser = new DocumentBlockParser();
+        activateBlockParser(this.documentBlockParser);
     }
 
     public static List<BlockParserFactory> calculateBlockParserFactories(List<BlockParserFactory> customBlockParserFactories) {
@@ -59,9 +66,6 @@ public static List<BlockParserFactory> calculateBlockParserFactories(List<BlockP
      * The main parsing function. Returns a parsed document AST.
      */
     public Document parse(String input) {
-        DocumentBlockParser documentBlockParser = new DocumentBlockParser();
-        activateBlockParser(documentBlockParser);
-
         int lineStart = 0;
         int lineBreak;
         while ((lineBreak = Parsing.findLineBreak(input, lineStart)) != -1) {
@@ -77,9 +81,23 @@ public Document parse(String input) {
             incorporateLine(Substring.of(input, lineStart, input.length()));
         }
 
-        finalizeBlocks(activeBlockParsers);
-        this.processInlines();
-        return documentBlockParser.getBlock();
+        return finalizeAndProcess();
+    }
+    
+    public Document parse(Reader input) throws IOException {
+        BufferedReader bufferedReader;
+        if (input instanceof BufferedReader) {
+            bufferedReader = (BufferedReader) input;
+        } else {
+            bufferedReader = new BufferedReader(input);
+        }
+        
+        String line;
+        while ((line = bufferedReader.readLine()) != null) {
+            incorporateLine(line);
+        }
+
+        return finalizeAndProcess();
     }
 
     @Override
@@ -472,6 +490,12 @@ private boolean finalizeBlocks(List<BlockParser> blockParsers) {
         return true;
     }
 
+    private Document finalizeAndProcess() {
+        finalizeBlocks(this.activeBlockParsers);
+        this.processInlines();
+        return this.documentBlockParser.getBlock();
+    }
+    
     private static class MatchedBlockParserImpl implements MatchedBlockParser {
 
         private final BlockParser matchedBlockParser;
diff --git a/commonmark/src/main/java/org/commonmark/parser/Parser.java b/commonmark/src/main/java/org/commonmark/parser/Parser.java
index d2c34f5c2..7d46dfb0d 100644
--- a/commonmark/src/main/java/org/commonmark/parser/Parser.java
+++ b/commonmark/src/main/java/org/commonmark/parser/Parser.java
@@ -1,5 +1,7 @@
 package org.commonmark.parser;
 
+import java.io.IOException;
+import java.io.Reader;
 import org.commonmark.Extension;
 import org.commonmark.internal.DocumentParser;
 import org.commonmark.internal.InlineParserImpl;
@@ -43,12 +45,23 @@ public Node parse(String input) {
         InlineParserImpl inlineParser = new InlineParserImpl(specialCharacters, delimiterCharacters, delimiterProcessors);
         DocumentParser documentParser = new DocumentParser(blockParserFactories, inlineParser);
         Node document = documentParser.parse(input);
+        return postProcess(document);
+    }
+    
+    public Node parseReader(Reader input) throws IOException {
+        InlineParserImpl inlineParser = new InlineParserImpl(specialCharacters, delimiterCharacters, delimiterProcessors);
+        DocumentParser documentParser = new DocumentParser(blockParserFactories, inlineParser);
+        Node document = documentParser.parse(input);
+        return postProcess(document);
+    }
+
+    private Node postProcess(Node document) {
         for (PostProcessor postProcessor : postProcessors) {
             document = postProcessor.process(document);
         }
         return document;
     }
-
+    
     public static class Builder {
         private final List<BlockParserFactory> blockParserFactories = new ArrayList<>();
         private final List<DelimiterProcessor> delimiterProcessors = new ArrayList<>();
diff --git a/commonmark/src/test/java/org/commonmark/test/ParserTest.java b/commonmark/src/test/java/org/commonmark/test/ParserTest.java
new file mode 100644
index 000000000..cc2dda1fc
--- /dev/null
+++ b/commonmark/src/test/java/org/commonmark/test/ParserTest.java
@@ -0,0 +1,37 @@
+package org.commonmark.test;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import org.commonmark.html.HtmlRenderer;
+import org.commonmark.node.Node;
+import org.commonmark.parser.Parser;
+import static org.junit.Assert.assertEquals;
+import org.junit.Test;
+
+public class ParserTest {
+    @Test
+    public void ioReaderTest() throws IOException {
+        Parser parser = Parser.builder().build();
+        
+        InputStream input1 = ParserTest.class.getResourceAsStream("/spec.txt");
+        Node document1;
+        try (InputStreamReader reader = new InputStreamReader(input1)) {
+            document1 = parser.parseReader(reader);
+        }
+        
+        InputStream input2 = ParserTest.class.getResourceAsStream("/spec.txt");
+        StringBuilder sb = new StringBuilder();
+        try (InputStreamReader reader = new InputStreamReader(input2)) {
+            int ch;
+            while ((ch = reader.read()) != -1){
+                sb.append((char)ch);
+            }
+        }
+        
+        Node document2 = parser.parse(sb.toString());
+        
+        HtmlRenderer renderer = HtmlRenderer.builder().escapeHtml(true).build();
+        assertEquals(renderer.render(document2), renderer.render(document1));
+    }
+}