During a ten-year period, 172 eyes of 155 patients developed acute symptomatic posterior vitreous detachments. The study included only patients examined within three months of the onset of symptoms. The patients ranged in age from 22 to 82 years, with an average age of 60 years. Of the 172 eyes, 118 (69%) developed no retinal or vitreous complications. Retinal tears occurred in 14 eyes (8%) and vitreous or retinal hemorrhages occurred in 36 eyes (21%). Seventeen patients (11%) who had acute symptomatic posterior vitreous detachment in one eye later developed acute symptomatic posterior vitreous detachment in the fellow eye. The second posterior vitreous detachment developed within two years of the first one in 15 eyes (88%). In 13 patients (76%), the second eye responded in the same manner to the posterior vitreous detachment as had the first, that is, ten pairs of eyes had no further complications, two pairs had retinal or vitreous hemorrhages, and one pair had retinal breaks.