We studied 65 rural hospitals in Missouri that provided obstetric services in 1986. The hospitals were divided into three groups on the basis of their physician obstetric staff: family or general practitioners only (38 hospitals), family practitioners and obstetricians (22 hospitals), and obstetricians only (five hospitals). From birth certificate data, we detected a decline in the mean number of births in all groups of rural hospitals comparing 1980-1983 with 1984-1987. Births in family practice only hospitals declined most over the past four years (35%), whereas there was only a 4 percent decline in the number of births to rural Missouri women. In 1987, 10 of the 38 family practice only hospital obstetric units closed due to loss of physician services, whereas none of the other hospitals stopped providing obstetric care (X2 = 8.40, p less than 0.005). These findings suggest that rural hospitals with family and general practitioners exclusively on their obstetric staffs are at significant risk of closing their obstetric units.