Four techniques for obtaining endometrial cultures in puerperal patients were compared in 18 uninfected women undergoing postpartum tubal ligation. Four culture specimens were obtained from each patient in the following sequence: transfundal aspiration, transcervical brush biopsy of the endometrium through a double-lumen catheter, transcervical lavage of the endometrial cavity through a doublelumen catheter, and aspiration of the secretions from the lower uterine segment through a single-lumen catheter. Quantitative cultures for aerobic and anaerobic bacteria were performed on all specimens. Cultures from the single-lumen aspirate had the greatest variety of different organisms and the highest colony counts of individual organisms. The brush and lavage techniques were equally effective in reducing, but not eliminating, contamination of endometrial specimens with cervical organisms. The authors conclude that, of the techniques evaluated in these uninfected patients, the most satisfactory procedure for routinely obtaining endometrial cultures is brush biopsy or lavage through a double-lumen catheter.