The aim of this study was to establish the aetiology and circumstances of meniscal injuries in the general adult population. We studied a group of patients who underwent arthroscopy under the care of the same surgeon between 1991 and 1998 (1236 patients). The study group included 392 patients, aged 18 to 60 years, with no previous knee injury, surgery or arthritis, with normal X-rays and meniscal injuries proven at arthroscopy. No professional athletes were included in the study group. The patients with Sports injuries (mean age 33 years) accounted for 32.4% of cases. The patients with Non-sporting injuries (mean age 41 years) accounted for 38.8% of tears. 71.9% of these happened in activities of daily living (and half of this group sustained their tear by squatting or ascent from this position). Patients without identifiable injury (mean age 43 years) represented 28.8% of cases. Male:Female ratio was 4:1. Medial tears accounted for two thirds of cases. This type of study, not undertaken since the advent of MRI or arthroscopy, shows that in the general population, two thirds of meniscal tears occurred in the absence of sporting activities, frequently within the ambit of every day activities and in the absence of the classic injury mechanism. Ascent from a squat is a common mechanism of injury not widely described or emphasised.