Lower lid retractor aponeurosis disinsertion is a well-recognized etiologic factor in many involutional entropion cases, but to our knowledge it has not previously been reported as a cause of congenital entropion. Four congenitally entropic lower eyelids in three patients with no history of birth trauma were all found to have retractor disinsertion during exploratory procedures. All four eyelids were surgically corrected by reinserting the retractors to the inferior tarsal margin. Detailed histologic studies of orbicularis oculi muscle fibers in two cases showed no evidence of fiber hypertrophy. This finding refutes the commonly accepted concept of orbicularis muscle hypertrophy as an etiologic mechanism of congenital entropion.