A traumatic cataract developed in a 17-year-old boy after he sustained penetrating trauma and underwent treatment of endophthalmitis. B-scan ultrasonography revealed a swollen lens and an accumulation of echoes on the posterior capsule. Two months later, this patient experienced sudden visual improvement, from hand motions to 20/25, associated with spontaneous rupture of the posterior capsule. This unusual occurrence may be due to increased intralenticular pressure or weakness in the lens capsule.