Five popular aspirin-containing analgesic preparations were compared with one another and with a placebo. In a group of 198 postpartum patients, all 5 preparations gave better relief from pain than did the placebo, and there were no significant differences among them during the first 3 hours of observation. In a second group of 60 patients, the 5 preparations were compared as to incidence of gastrointestinal disturbances. Two of the preparations which contained acetophenetidin were associated with an incidence of "upset stomach" significantly higher than were the remaining 3 preparations or the placebo, and the last 4 did not differ significantly from one another in this respect. With negative results, a third group of 9 patients was studied systematically for subjective or objective differences as to pain relief or other effects caused by the 5 preparations.