Abstract: It is not common to diagnose a medical condition as another condition based on clinical features and investigations which later turns out to be normal because of a congenital lesion. There are many lesions reported mimicking Diaphragmatic Hernia which were treated or found during when operated for the other diagnosis. Here we report a case of Pleural effusion on the left side which was treated as Tuberculosis pleural effusion later which was found to be a congenital Diaphragmatic hernia in a middle age male.