Various factors ; i.e., maternal and fetal conditions, method of ansthesia, induction delivery time (IDT), induction uterine incision time (1UT), uterine incision - delivery time (UDT), surgical experience (specialists vs. residents), and gestational age ; which might intluence neonatal outcome follwing cesarean section were investigated in sixty-one patients who underwent cesarean section at Han Yang University Hospital between August 1992 and March 1993. Neonatal outcome was assessed by 1-and 5-minute Apgar scores, and umbilical vein blood gas analysis (UVBGA) taken immediately after birth. The results were as follows. 1) Preoperative maternal conditions did not affect neonatal outcome. For the neonates of normal and abnormal maternal conditions, the 1-minute Apgar score were 7.2±1.0 and 6.8±1.0, respectively. In the same groups of neonates, The UVBGA showed pHa 7.33±0.04 and 7.33±0.05; PaCO2 44.7±5.1 and 44.4±7.4 mmHg; PaO2 30.5±7.1 and 27.9±6.3 mmHg; and BE -2.7±3.5 and -3.8±3.5 mEq/L, respectively. 2) Method of anesthesia did not change neonatal outcome. In the general and epidural anestheia groups, the 1- minute Apgar scores were 7.1±1.0 and 7.3±0.8, respectively. The UVBGA in the same groups showed pHa 7.33±0.05, 7.34±0.03; PaCO2 44.6±6.1, 41.0±6.1 mmHg ; PaO2 29.5±6.8, 28.7±6.6 mmHg; and BE -3.2±3.5, -4.0±3.6 mEq/L, respectively. 3) IDT did not influence neonatal outcome. In the groups with IDT exceeding or equal to 10 ininutes and less than 10 minutes, the 1-minute Apgar scores were 7.2±1.0 and 7.0±1.0 with IDT, respectively. In the same groups, the UVBGA revealed pHa 7.33±0.04, 7.33±0.05; PaCO2 40.0±6.2, 44.9±6.1 mmHg; PaO2 28.8±7.1, 29.9±6.7 mmHg; and BE -2.8±3.5, -3.8±3.5 mEq/L, respectively. IDT was more than 10 minutes in all epidural anesthesia cases. 4) In the groups with UDT more than or equal to 3 minutes and less than 3 minutes, the 1- minute Apgar scores were 7.0±1.1 and 6.7±1.6, respectively. In the same groups, the UVBGA revealed pHa 7.32±0.05, 7.33±0.05; PaCO2 41.8±5.1, 44.4±6.4 mmHg; PaO2 28.3±6.2, 29.5±6.9 mmHg; and BE -3.9±3.6, -5.0±2.8 mEq/L, respectively. 5) Surgical experience did not contribute to the neonatal outcome. The 1-minute Apgar scores were 7.2±1.0 and 7.0±1.1 in the groups where cesarean section were performed by specialists and residents, respectively. UVBGA showed PHa 7.33±0.04, 7.32±0.06; PaCO2 44.8±6.5, 44.3±5.8 mmHg; PaO2 30.2±6.9, 28.5±6.9 mmHg; and BE -2.6±3.4, -3.9±3.6 mEq/L, respectively in the same groups. 6) Gestational age, determined as fullterm or preterm did not influence neonatal outcome. In the fullterm and preterm neonates, the 1-minute Apgar scores were 7.1±1.0 and 6.6±1.1, respectively. UVBGA showed pHa 7.33±0.05, 7.32±0.05; PaCO2 44.5±6.3, 45.0±4.9 mmHg ; PaO2 29.4±6.9, 30.0±6.6 mmHg ; and BE -3.2+3.6, -2.7+2.1 mEq/L respectivly. It appears that maternal and fetal conditions, method of anesthesia, IDT and UDT, experience of surgery, and gestational age do not influence post-cesarean neonatal outcome.