The fractional removal rate of exogenous triglycerides (TG) in 12 obese subjects with a mean body weight of 132+/-5 kg (S.E.M.) has been studied before a jejunoileal shunt operation. The study was repeated postoperatively at stable body weights 30-54 months later. The weight loss ranged from 13 to 65 kg (mean weight reduction 27%). In 8 patients, 0.3-6.0 kg of skin and subcutaneous tissue were removed surgically for cosmetic reasons during the weight reduction period. Serum cholesterol fell from 220+/-8 to 141+/-11 mg/100 ml (p less than 0.001). The serum TG reduction was not significant, 1.80+/-0.25 before and 1.50+/-0.19 mmol/l after operation. The fractional removal rate of exogenous TG, determined by the intravenous fat tolerance test (IVFTT) with the Intralipid fat emulsion, was not significantly changed. The IVFFT k2 value was 3.5+/-0.5%/min before and 4.3+/-0.6 after surgery (p greater than 0.05). Previous studies have shown that a major part of Intralipid is removed initially in skeletal muscle. The unchanged fractional removal rate of Intralipid, despite the marked reduction in the amount of adipose tissue, supports the concept that the adipose tissue may play a minor role in the initial elimination of exogenous TG from the bloodstream.