The hypothesis that the lipid emulsion of the emulsion formulation of propofol is responsible for the low frequency of nausea, retching, and vomiting after propofol anesthesia was tested. A randomized, prospective, and comparative study was performed to evaluate the antiemetic effect of 10% lipid solution in 60 women, ASA physical status I and II, scheduled for ambulatory laparoscopic procedures. Two groups of patients were studied. Induction of anesthetia (thiopental) and maintenance of anesthesia (enflurane, nitrous oxide) were similar in both groups. At induction the study group received 10% Intralipid (3 mL/min for 20 min). The control group received 5% dextrose in lactated Ringer''s solution at the same time. Other drugs administered during or after anesthesia were similar among the groups. The groups were similar with respect to duration of anesthesia, characteristics of early and intermediate recovery, as well as pain scores in the postanesthesia care unit. There were no differences in the amount of antiemetic medications administered or postoperative nausea, retching, or vomiting when the patients were evaluated objectively by a blinded observer or subjectively by patient self-evaluation. It is concluded that 10% Intralipid, the lipid in the emulsion formulation of propofol, does not possess significant antiemetic effects.