diff --git a/dart/0205-isomorphic-strings.dart b/dart/0205-isomorphic-strings.dart
new file mode 100644
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+++ b/dart/0205-isomorphic-strings.dart
@@ -0,0 +1,29 @@
+// Time Complexity: O(n)
+// Space Complexity: O(1)
+
+class Solution {
+  bool isIsomorphic(String s, String t) {
+    if (s.length != t.length) return false;
+
+    Map<String, String> sToT = {};
+    Map<String, String> tToS = {};
+
+    for (int i = 0; i < s.length; i++) {
+      String currS = s[i]; 
+      String currT = t[i];
+
+      if (sToT.containsKey(currS) && sToT[currS] != currT) {
+        return false;
+      }
+
+      if (tToS.containsKey(currT) && tToS[currT] != currS) {
+        return false;
+      }
+
+      sToT[currS] = currT;
+      tToS[currT] = currS;
+    }
+
+    return true;
+  }
+}