During the 10-year period from 1970 to 1979, a total of 115,096 deliveries occurred at the Los Angeles County/University of Southern California Medical Center. Of these, 47,567 patients (41.3%) were monitored during labor and delivery. The intrapartum monitoring technique was initially introduced in late 1969. The monitoring rate increased gradually from 18% in 1970 to 74% in 1979. The perinatal mortality rate during this 10-year period was 24.4/1,000. The perinatal mortality rate decreased in an inverse proportion to the monitoring rate. The main portions of the decrease in perinatal mortality rate were in the intrapartum and neonatal death rates. Both the fetal death rate and the neonatal death rate were significantly lower in the monitored patients than in those who were not monitored. This was irrespective of the fact that most high-risk patients were included in the monitored group. The cesarean section rate during this period increased slightly from 9.3% in 1970 to 12.3% in 1979. The primary cesarean section rate increased from 6.4% in 1970 to 8.7% in 1979. These findings suggest the beneficial role of intrapartum fetal monitoring and its association with diminished perinatal losses.