Background:The purpose of this study was to investigate the extent of antenatal care coverage as well as causes for and factors associated with the failure of pregnant mothers to register for antenatal care. Patients and Methods: During 1997, a list was compiled for births in three urban and three rural primary health care centers in the Northern region of Saudi Arabia, which contained details as to whether or not the mothers had been registered for antenatal care during their pregnancy. A number of nonregistrants and a similar number of registrants were interviewed at their homes, and a predesigned questionnaire was completed. In the urban areas, comparisons were made between mothers who' attended 'private clinics for antenatal care and those who received no care. Logistic regression analysis was performed to show the effects of socioeconomic factors on registration for antenatal care at local primary health care centers. Results: About 66.9% and 95.9% of mothers in urban and rural areas, respectively, were found to have registered at their local health centers. It was found that 9.7% and 2.6% of urban and rural mothers, respectively, never received antenatal care. In urban areas, the main causes for not seeking antenatal care included mothers' belief that pregnancy is a normal event, and, therefore, there is no need for care (68.8%), or was the result of a husband or mother being busy (28.8% and 27.5%, respectively), making it difficult for the mother to get to an antenatal center. Analysis of the study showed that mothers who attended private clinics for care were more likely to be of a high socioeconomic status and with relatively small family sizes. On the other hand, mothers who never received antenatal care were more likely to be of low socioeconomic status and living a distance away from a health center. Results of logistic regression analysis showed that the level of education of the mother and her husband had a significant effect on registration for antenatal care at local primary health care centers. Conclusion: We conclude that antenatal care is high in rural areas, but in urban areas, there is still room for improvement. Outreach services as well as health education on the benefits of pregnancy check-ups, especially for mothers at risk of defaulting, could contribute to more antenatal care coverage.