AbstractA double‐blind trial was carried out on 124 randomized patients with acute viral hepatitis, of whom 58 were treated with (+)‐cyanidanol‐3 in a dose of 3 gm per day and 66 with placebo. The treatment was given for 50 days. At 5‐day intervals, SGPT, SGOT, and total serum bilirubin levels were tested. For the total group of patients, the levels of SGPT and SGOT activity were significantly lower in the cyanidanol group than in the control group from 30th to 50th day of treatment (with exception of SGOT at Day 35) (Student's t test: p between 0.01 and 0.05).In 35 patients with acute hepatitis caused by hepatitis A virus, 17 treated with cyanidanol and 18 controls, no significant differences for either SGPT and SGOT were observed. In 58 patients with acute hepatitis caused by hepatitis B virus, 27 treated with cyanidanol and 31 controls, a trend in favor of the cyanidanol group was observed after 30 days of treatment in SGPT activity, the difference being statistically significant after 45 days of treatment (p<0.05). There was also a trend in favor of the cyanidanol group for SGOT activity from the 30th to 45th day of treatment (p between 0.05 and 0.10). In 31 patients with acute hepatitis caused by hepatitis non‐A, non‐B virus, 14 treated and 17 controls, a significant difference between the groups, in favor of the cyanidanol group was observed for both SGPT and SGOT after 40 and 45 days of treatment (p<0.05). The effect of cyanidanol on the transaminases appeared to be a suppression of the “rebounds” occurring from Day 30 onward. There were no significant differences in the evolution of levels of total serum bilirubin.Among the patients with acute hepatitis caused by hepatitis B virus, 10 of the 27 patients treated with cyanidanol became HBsAg negative after 50 days of treatment compared to 16 of 31 in the control group. This difference is not statistically significant. Cyanidanol had no effect on carrier state. Since patients who show rebounds in levels of serum transaminase activity after apparent recovery from the initial phase usually undergo a more prolonged convalescence, it appears that treatment with (+)‐cyanidanol‐3 could be useful in shortening the total duration of their illness. It is essential that the investigations of the effects of drugs in viral hepatitis be performed on well‐defined etiological