diff --git a/.changeset/smart-humans-cover.md b/.changeset/smart-humans-cover.md
new file mode 100644
index 000000000..4408e0a9c
--- /dev/null
+++ b/.changeset/smart-humans-cover.md
@@ -0,0 +1,5 @@
+---
+'mermaid': patch
+---
+
+fix: Update flowchart direction TD's behavior to be the same as TB
diff --git a/packages/mermaid/src/diagrams/flowchart/flowDb.spec.ts b/packages/mermaid/src/diagrams/flowchart/flowDb.spec.ts
index 44a6ed052..3e4034e3d 100644
--- a/packages/mermaid/src/diagrams/flowchart/flowDb.spec.ts
+++ b/packages/mermaid/src/diagrams/flowchart/flowDb.spec.ts
@@ -165,3 +165,20 @@ describe('flow db getData', () => {
     expect(edges[3].curve).toBe('stepBefore');
   });
 });
+
+describe('flow db direction', () => {
+  let flowDb: FlowDB;
+  beforeEach(() => {
+    flowDb = new FlowDB();
+  });
+
+  it('should set direction to TB when TD is set', () => {
+    flowDb.setDirection('TD');
+    expect(flowDb.getDirection()).toBe('TB');
+  });
+
+  it('should correctly set direction irrespective of leading spaces', () => {
+    flowDb.setDirection(' TD');
+    expect(flowDb.getDirection()).toBe('TB');
+  });
+});
diff --git a/packages/mermaid/src/diagrams/flowchart/flowDb.ts b/packages/mermaid/src/diagrams/flowchart/flowDb.ts
index b729a85e0..632633730 100644
--- a/packages/mermaid/src/diagrams/flowchart/flowDb.ts
+++ b/packages/mermaid/src/diagrams/flowchart/flowDb.ts
@@ -406,7 +406,8 @@ You have to call mermaid.initialize.`
    *
    */
   public setDirection(dir: string) {
-    this.direction = dir;
+    this.direction = dir.trim();
+
     if (/.*</.exec(this.direction)) {
       this.direction = 'RL';
     }