We retrospectively reviewed 57 open patella fractures treated at our institution between 1976 and 1989. Forty-four patients with 47 fractures (cases) were available for follow-up a mean of 9.4 years after injury (range 2.2-15.7). High-energy vehicular trauma was the cause of injury in > 90% of cases. Treatment included osteosynthesis in 50% of cases and patellectomy (partial or total) in the remainder. At follow-up evaluation, results were excellent in 17% of cases, good in 60%, fair in 17%, and poor in 6%. Nonunion occurred in two cases in which nonrigid internal fixation was used. The incidence of deep infection was 10.7%, and the infection rate correlated with the magnitude of soft-tissue injury. Two of the seven fractures (29%) treated with cerclage wiring became infected. None of the open type I and II fractures treated with immediate internal fixation or primary wound closure (or both) became infected. Therefore, we recommend immediate rigid internal fixation (other than cerclage wiring) of types I and II open patella fractures. Partial patellectomy of highly comminuted fractures provided results similar to those of internal fixation of less comminuted fractures. Thus, when comminution precludes fixation, partial patellectomy can be performed without hesitation. The timing of wound closure should be individualized.