Perinatal health care is an important part of a nation's health care system. In the Nordic countries this type of health care is provided by the national public health systems without cost for the women. The societal costs of the care provided have, however, not been known. The aim of the present study was to estimate societal costs of antenatal and obstetrical care in a Norwegian county during a twelve month period 1988-89. A total of 1908 women delivered during the registration period. The mean total cost was estimated to NOK 36.300 per woman. Primary care antenatal visits accounted for 8%, outpatient visits (inclusive ultrasound screening) 4%, and hospital care in connection with delivery represented 36% of the total cost. The major determinant of societal costs was sick leave during pregnancy, contributing 43% to the total cost. This underlines the importance of the ongoing debate about sick leave in pregnancy. The mean cost of primary care based antenatal care, averaging 10.8 visits per woman, was estimated to NOK 2.800. An important factor was use of patients' own time, accounting for 35% of this amount. The prevalence at the time of admission for delivery of five important complications or obstetrical conditions (pre-eclampsia, placenta previa, intrauterine growth retardation, twin pregnancy, and breech presentation) was recorded. The mean total societal cost for women with the indicator conditions was approximately one fifth greater than for women without any of the indicator conditions.