To investigate the effect of PGF₂α treatment on prevention of retained placenta and on subsequent reproductive performances of induced-and spontaneous-parturient cows, 151 heads of Holstein cows raised at National Animal Breeding Institute were used. The parturition was induced by injecting 20 ㎎ of dexamethasone into cows at 5 days perior to expected calving date, and to prevent retained placenta a single dose of 10 ㎎ PGF₂α was injected i.m. within 1 hour after induced-or spontaneous-calving. The cows which did not expelled their placenta until 12 hours postparturient were termed as the cow of placenta retention. The calving of cows was induced at 45.5±2.0 hours after injection of dexamethasone. PGF₂α injection after calving to the induced-calving cows resulted in a greater reduction(P$lt;0.01) of incidence of placenta retention (27.3%)than physiologycal saline injected cows (9.09%) In days to the Ist service after calving, there was no significant difference(P$lt;0.05) between spontaneous and PGF₂α treatment after induced-calving, but physiological saline injection after induced-calving cows resulted in significantly(P$lt;0.05) longer days(106.5±27.5 days) than spontaneous calving(66.5±4.1 days). A single dose of 10 ㎎ PGF₂α to 35 spontaneous-calving cows did not significantly(P$lt;0.05) preventive effect on placenta retention (25.7%) compared with physiological saline treatment.