Throughout medical science today there is increasing emphasis upon understanding the familial and associated genetic interplay in various disease processes. We observed a case of Legg-Calve-Perthes disease developed in monozygotic male twins. They have some mirror image of each other, for example hair whorl and involved hip. This report of the disease which is present in mirror fashion in idenitical twins illustrates enen more vividly the genetic interaction in the disease. Therefore, those who are aware that Legg-Calve- Perthes disease has appeared in a family should keep in mind the probability of the disease developing in another member.