To observe the effect of acute ethanol ingestion on stable lipid transport in intestinal lymph, three groups of mesenteric lymph fistula rats were prepared. In group A rats, lipid emulsion containing 120 mumol/hr of oleate (control meal) was infused intraduodenally for 8 hr. Group B rats were infused with another lipid emulsion, which had the same basic composition as the control meal but included 0.75 g/kg body weight/hr of ethanol (alcohol meal), for 8 hr. In group C, rats were infused with the control meal for the first 4 hr, then with the alcohol meal for the next 4 hr. Lymph flow increased just after the infusion of ethanol, that is, lymph flow in group B was significantly higher than that of group A at 1 and 2 hr, and lymph flow in group C was significantly higher than that of group A at 5 hr. In group A, lymphatic triglyceride (TG) output reached a plateau of more than 30 mumol/hr after 3-hr infusion. TG output in group B was significantly lower than that in group A from 2 hr to 8 hr and was two-thirds that of group A at the plateau level. In group C, TG output was the same as in group A until 5 hr, but decreased to two-thirds of that in group A at 6 hr, 2 hr after replacing the control meal with the alcohol meal. Lymphatic phospholipid output exhibited a tendency similar to that of TG output. Comparisons of group A vs. B and A vs. C clearly demonstrated an inhibitory effect of ethanol on stable lipid transport in intestinal lymph. A 2-hr infusion was enough for ethanol to exhibit its inhibitory effect. In conclusion, stable lymphatic transport of intestinal absorbed lipid was suppressed by acute ethanol ingestion.