Purpose: To find a protocol radiographic follow-up of the contralateal hip survival appropriate for patients with inilateal nontraumatic osteonecrosis of femoral head. Methods: We retrospectively reviewed the radiographs of 130 patients who had been unilaterally affected by non-traumatic osteonecrosis of femoral head (including alcohol-induced, and idiopathic osteonerosos). The time when osteonecrosis occurred in the contralateral hip was noted. The hipswere followed for an average of 16.56 (0.5~84) months. Results: The survival of the contralateral hip progressively declined during the period of follow-up. The contralateral hip survival rates, using ARCO stage II and stage III as the end points, were 65.1% and 66.0% respectively at two years. At no time did the deterioration in survival accelerate or slow down. Conclusion: We conclude that the continues to deteriorate thereafter. We did not find an optimal protocol of radiographic follow-up for contralateral hip in cases with unilateral osteonecrosis of femoral head. To detect osteonecosis of contralateral hip at its early stage by radiography, radiographs should be taken as frequently as once every 3 months for more than two years.