We reviewed eight patients over 50-years old, with an initial diagnosis of medial meniscal tear confirmed with magnetic resonance imaging (MRI) and with no evidence of osteonecrosis. After arthroscopic meniscectomy, all patients had recurrent aggravated knee pain and reevaluation with MRI showed images compatible with osteonecrosis. The average age was 65 years (range 54 to 75 years). The mean time from MRI to surgery was 8 weeks (range 1 to 28 weeks). In five patients a total meniscectomy, and in three a partial meniscectomy with recontouring of the meniscus were performed. Surgical treatment was initially successful, but all eight patients returned to our office with recurrent aggravated pain in the treated knee. Reevaluation with MRI, at an average of 18 weeks postoperatively, found abnormalities at the medial condyle consistent with osteonecrosis. The purpose of this study is to report a potentially serious outcome after arthroscopic meniscectomy in patients over 50-years old.