diff --git a/.changeset/unlucky-bags-shake.md b/.changeset/unlucky-bags-shake.md
new file mode 100644
index 000000000..622d47fdd
--- /dev/null
+++ b/.changeset/unlucky-bags-shake.md
@@ -0,0 +1,5 @@
+---
+"myst-to-md": patch
+---
+
+Add iframes and directives to markdown export
diff --git a/packages/myst-to-md/src/directives.ts b/packages/myst-to-md/src/directives.ts
index abed4201b..624ffe1bc 100644
--- a/packages/myst-to-md/src/directives.ts
+++ b/packages/myst-to-md/src/directives.ts
@@ -361,12 +361,33 @@ function tabItem(node: any, _: Parent, state: NestedState, info: Info): string {
   return handler(node, _, state, info);
 }
 
+function iframe(node: any, _: Parent, state: NestedState, info: Info): string {
+  const handler = writeStaticDirective('iframe', { argsKey: 'src', keys: IMAGE_DIRECTIVE_OPTS });
+  return handler(node, _, state, info);
+}
+
+function aside(node: any, _: Parent, state: NestedState, info: Info): string {
+  const name = node.kind ?? 'aside';
+  const admonitionTitle = select('admonitionTitle', node);
+  const args = admonitionTitle ? state.containerPhrasing(admonitionTitle as any, info) : '';
+  const nodeCopy = {
+    ...node,
+    children: node.children.filter((n: GenericNode) => n.type !== 'admonitionTitle'),
+  };
+  const options = {
+    keys: ['class'],
+  };
+  return writeFlowDirective(name, args, options)(nodeCopy, _, state, info);
+}
+
 export const directiveHandlers: Record<string, Handle> = {
   code,
   image,
   container,
   admonition,
   details,
+  iframe,
+  aside,
   card,
   grid: writeFlowDirective('grid', undefined, {
     keys: ['columns'],
diff --git a/packages/myst-to-md/tests/directives.yml b/packages/myst-to-md/tests/directives.yml
index eb494005f..77fc8d44c 100644
--- a/packages/myst-to-md/tests/directives.yml
+++ b/packages/myst-to-md/tests/directives.yml
@@ -877,3 +877,46 @@ cases:
       Tab two
       :::
       ::::
+  - title: iframe
+    mdast:
+      type: root
+      children:
+        - type: iframe
+          src: https://example.com
+          width: 10%
+    markdown: |-
+      ```{iframe} https://example.com
+      :width: 10%
+      ```
+  - title: aside
+    mdast:
+      type: root
+      children:
+        - type: aside
+          class: my-class
+          children:
+            - type: paragraph
+              children:
+                - type: text
+                  value: Aside content
+    markdown: |-
+      :::{aside}
+      :class: my-class
+
+      Aside content
+      :::
+  - title: topic
+    mdast:
+      type: root
+      children:
+        - type: aside
+          kind: topic
+          children:
+            - type: paragraph
+              children:
+                - type: text
+                  value: Topic content
+    markdown: |-
+      :::{topic}
+      Topic content
+      :::