Responses of national samples of 329 residency-trained family physicians and 237 obstetricians were studied to determine the attitudes of family physicians and obstetricians toward the practice of obstetrics by family physicians. The attitudes of obstetricians and family physicians varied greatly, and the attitudes of obstetricians toward obstetric care provided by family physicians tended to become less supportive following the time of the obstetricians' training. In particular, obstetricians felt strongly that family physicians were inadequately trained to provide uncomplicated obstetric care. These negative attitudes were reflected in obstetricians' opinions regarding hospital obstetric privileges for family physicians. From a list of 11 obstetric privileges, obstetricians indicated that residency-trained family physicians should be granted a mean of 2.2 privileges, while family physicians who currently practice obstetrics indicated a mean of 6.6 (P less than .001). Family physicians who felt well supported by obstetricians during their obstetric training were more likely to develop positive attitudes toward obstetric practice than those who were not well supported. Both obstetricians and family physicians indicated that the adequacy of maternity care in rural areas would decline if family physicians withdrew from maternity care. There was strong agreement that rising malpractice premiums may soon force family physicians to stop delivering babies. This study concludes that there are vast differences among obstetricians and family physicians in perceptions regarding obstetric practice by family physicians which may adversely affect such practice.