Intravenous fat tolerance tests (IVFTT) were performed in 13 healthy men volunteers once a day during three consecutive days in order to compare three different fat emulsions randomly administered (Intralipid 20%, Hausmann Lipid 20%, Lipovenös 20%). The amount of fat was 0.1 g/kg of body weight injected within 32 +/- 4 sec and the lipid clearance was determined over 40 min. The fractional removal rates k for the three different emulsions of fat were 5.38 +/- 1.67, 4.95 +/- 2.15, 3.92 +/- 1.31 %/min, respectively (mean +/- SD), and the half-life time of clearance T1/2 were 14.5 +/- 5.8, 16.9 +/- 7.4, 19.2 +/- 5.2 min, respectively. The highest fat particles values were observed 5 min after the bolus and all concentrations remained within the normal range (0-3 g/liter) during the study. In addition, no adverse effects were observed throughout the IVFTT. The nonparametric analysis of variance (Friedman's test) showed no significant differences between groups, even if Lipovenös 20% tended to be cleared more slowly than Intralipid 20%. These results suggest that the three fat emulsions are similarly eliminated from the blood stream and do not result in acute intolerance. Further studies based on prolonged infusion should be carried out to determine whether the two new emulsions might be alternatively used for intravenous nutritional support.