The relations between clinical signs of infection and postoperative endometritis were studied among 429 women with negative preoperative chlamydial and gonococcal cultures. Clue cells and a vaginal smear not dominated by rods and positive amine tests were more common among the 12 patients (2.8%) with endometritis. In the stepwise logistic regression procedure the presence of greater than 20% clue cells remained statistically significant and was associated with the highest relative risk, 5.6, with 95% confidence limits 1.82-17.2. This also implies clinical significance--women with clue cells constitute a group at risk of postabortal endometritis.