Over a 1-hr period, 52 Chinese and Japanese men (mean age 25.4 yr) and 11 Caucasians (mean age 24.8 yr) drank 0.4 ml of ethanol per kg of body weight divided in 4 equal doses (as 19% solution). Of the Orientals, 33 developed a cutaneous flush, sometimes accompanied by a reaction resembling hives, while 1 Caucasian flushed mildly. Blood was sampled before drinking and at 30, 60 and 120 min after the 1st drink for measurements of ethanol, acetaldehyde, histamine, testosterone, luteinizing hormone and hydrocortisone levels. The decrease in mean level of serum hydrocortisone was smaller in Orientals than in Occidentals and smaller in Orientals who were severe flushers than in Orientals who were nonflushers. Although no other biochemical measure correlated significantly with flushing, a significantly higher level of acetaldehyde was observed in Orientals than in Occidentals at 30 min.