Osteonecrosis of the medial femoral condyle is an uncommon complication of meniscal surgery. Whether this disease is associated with the original medial meniscus lesion or with the arthroscopic procedure is not yet known. We present two cases in which osteonecrosis has developed shortly after arthroscopy was performed for medial meniscus pathology. Magnetic resonance imaging has been the best tool to diagnose and follow up the changes in the involved area. Concerning the etiology, the authors raise the question of whether the medial compartment overloading observed in both of these cases had any significant meaning. Osteonecrosis following meniscal surgery in relatively young patients seems to have a good prognosis when correctly treated, with avoidance of weight bearing.