In a retrospective cohort study of ankle inversion injuries performed after the 1991-1992 season in the top two divisions of the Norwegian Volleyball Federation, 63 injuries were found among 318 players during 60,612 hours of training and 928 matches. The study was limited to acute ankle inversion injuries that caused an absence of 1 or more days from training or match play. The total injury rate was 0.9 +/- 0.12 per 1000 player hours: 0.7 +/- 0.11 during training and 2.6 +/- 0.56 during match play. The relative risk of injury during match play versus training was 3.9 (P < 0.001). Women had an injury rate of 1.1 +/- 0.18, whereas that of men was 0.7 +/- 0.15 (relative risk = 1.47; not significant). Most of the players (78%) had suffered at least one previous injury of the affected ankle. Most injuries were mild to moderate. The majority of the injuries (86%) occurred at the net, mainly when landing after blocking (63%) or attacking (29%). We suggest that simple measures such as rule changes, technical training, and prophylactic taping or bracing may lead to a significant reduction in the incidence and severity of such injuries.