Although preservation of meniscal tissue is paramount, there are occasions when repair of a torn meniscus is not possible. The surgical option may be a partial meniscectomy, the objective being to alleviate the patient's symptoms with resection of only that portion of the meniscus that is no longer functioning but is the cause of symptoms. Previous studies have questioned the need to perform such surgery and have recommended nonoperative treatment instead. Our goal was to compare the outcome of partial meniscectomy with that of physiotherapy alone for irreparable meniscal tears. Clinical outcome following arthroscopic partial meniscectomy may differ from that following physiotherapy alone, for patients with symptomatic irreparable meniscal tears. Nonrandomized prospective cohort study. Level 2. Patients satisfying the inclusion criteria chose to undergo knee arthroscopy (group A) or physiotherapy (group B). The diagnosis of a meniscal tear was made on physical assessment and magnetic resonance imaging examination. The meniscal tear was preventing them from continuing with their regular weightbearing exercise. Outcomes of interest were the following patient-reported outcomes (PROs): the Knee Osteoarthritis Outcome Score (KOOS) and Tegner Activity Score (TAS), with minimal clinically important differences being 10 and 1, respectively. PROs were completed at baseline, and at 1-year and 2-year follow-up. Changes in scores within and between groups were compared using analysis of variance and Wilcoxon tests (P <0.05). A power analysis demanded 65 patients in each group to produce a power of 80% and a P value of 5%. Of 528 patients enrolled in the study, 10 were lost to follow-up and 8 were excluded. Data were complete for 269 in group A, and 228 in Group B. Group A and B were similar in terms of age (41.1 years, SD 7.8 vs 40 years, SD 13.3), body mass index (22.5 kg/m2, SD 3.1 vs 23.1 kg/m2, SD 2.3), radiographic grade of osteoarthritis (median grade 2, range 0-3 in both groups), gender (male:female = 134:135 vs 112:116), and duration of symptoms (44.4 days, SD 5.6 vs 46.6 days, SD 8.8), with P >0.05. At both 1-year and 2-year follow-up, Group A had higher scores in the mean total KOOS (88.8, SD 8.0 vs 72.4, SD 3.8), as well as in all subscales within the KOOS, and the TAS (median 7, range 5-9 vs median 5, range 3-6), with P <0.001 for each variable. Performing a knee arthroscopy with partial meniscectomy is associated with improved KOOS and TAS, relative to treatment with physiotherapy alone, at 2-year follow-up. Physically active patients with symptomatic irreparable meniscal tears may experience a better clinical outcome following knee arthroscopy, relative to to physiotherapy alone.