We describe three cases of osteonecrosis of the femoral head (ONFH) in which the extent of necrosis increased after repeated episodes of ischemic attack. In all cases the evidence for two different ischemic attacks was clearly seen on MR images. The significance of the recurrent ischemic attacks is not clear yet but the detectable incidence of recurrence seems to be very low. We discuss the possibility that the increased extent of osteonecrosis may be the result of multiple ischemic attacks.