PURPOSE: To determine the clinical sequelae of nondegenerative peripheral vertical medial meniscus tears treated with abrasion and trephination alone (stable tears) or suture repair (unstable tears). Type of Study: Cohort follow-up. METHODS: At the time of anterior cruciate ligament reconstruction, 548 patients had nondegenerative peripheral vertical medial meniscus tears that were either left unsutured or repaired. Of 548 menisci, 233 were stable and were abraded and trephined (AT group), 139 were stable and left in situ (Situ group), and 176 were unstable and were repaired with sutures (Suture group). An unstable tear was defined as a torn meniscus that could be displaced into the intercondylar notch with a probe. Patients who had no medial or lateral meniscal tears at the time of ACL reconstruction served as a control population (No Tear group, n = 526). Subjective follow-up was obtained with a modified Noyes questionnaire. RESULTS: Objective follow-up was obtained at a mean of 4.8 +/- 1.7 years postoperatively. Subjective follow-up was obtained at a mean of 7.3 +/- 3.4 years postoperatively. At a mean of 3.7 years (range, 4 months to 10.7 years) after the reconstruction, a subsequent arthroscopy was required for 14 patients (6.0%) in the AT group, 15 patients (10.8%) in the Situ group, 24 patients (13.6%) in the Suture group, and 15 patients (2.9%) in the No Tear group; these numbers were not statistically significant. The mean total subjective score was not statistically significantly different between groups. CONCLUSIONS: Repaired unstable peripheral vertical medial meniscus tears have a failure rate of 13.6%, most retears occurring more than 2 years after repair. Of stable peripheral vertical medial meniscus tears treated with abrasion and trephination, most (94%) remain asymptomatic without stabilization.