As family and general practitioners who provide a substantial portion of the obstetric care in rural areas quit their obstetric practice, small rural hospital obstetric units are at risk of closing. Using a case study design, we examined the impact of the loss of obstetric services at a small rural hospital in Missouri. This unit was the site of delivery for less than one-half of the infants born to women living within its service area. However, it was the most likely source of care for women who were young, undereducated and unmarried (p less than 0.01). Evidence derived from birth certificates showed that women who delivered there had good perinatal outcomes compared with local women who delivered at larger hospitals. A gradual decline in the number of physicians providing obstetric care preceded the closing of the hospital unit. Women from the hospital service area who presented late for prenatal care were twice as likely to have had a low birthweight infant in the year after the local hospital unit closed (16.7% versus 7.4%), although this difference and other comparisons of outcomes were not statistically significant.