These experiments were carried out to investigate the effect of addition of estrous cow serum(ECS), amniotic fluid(AF) and AF + FCS on maturation of bovine oocytes in vitro. The oocytes with cumulus cells and unfragmented cytoplasm were used. The oocytes were matured in vitro for 24 hr in a CO₂ incubator with 5% CO₂ in air at 38.5℃. The medium used for maturation was TCM 199 and Ham`s F10 supplemented with hormones and antibiotics. The results obtained are as follows : I. When the oocytes were cultured in TCM (99 medium, maturation rate of oocyte in FCS 10%. ECS 5, 10, 15 and 20% was 70.0, 74.4, 75.0, 78.1 and 58.8%, respectively. There were no significant (p$gt;0.05) difference among the treatments. 2. When the oocytes were cultured in Ham`s F10, maturation rate of oocyte in AF 0, 10, 50 and 100% was 63.0, 87.3, 63.6 and 7.8%, respectively. AF 10% showed significantly (p$lt;0.05) higher maturation rate than others. 3. When the oocytes were cultured in Ham`s F10, maturation rate of oocyte FCS + AF showed significantly (p$lt;0.05) higher maturation rate(76.9%) than FCS only (50.8%).