This study examined the quality of data for delivering mothers and their newborns (April 1, 1984 to March 31, 1995) recorded by the Canadian Institute for Health Information (CIHI). The number of illogical and out-of-range values in the CIHI data were quite few; the occurrence of maternal and infant diseases estimated from CIHI data was quite similar to that in the literature; and major medical/obstetric complications recorded in CIHI were, in general, good predictors of adverse pregnancy outcomes. The authors conclude that CIHI data contain some of the information pertinent to perinatal surveillance that may be used to monitor maternal and infant health and to assess intrapartum care and hospital resource utilization. To adequately monitor and analyze patterns of health determinants and outcomes in all pregnant women and their infants in Canada, additional data collection mechanisms are needed to cover all recognized pregnancies and to collect antenatal and postpartum information and more detailed information on intrapartum care.