We have conducted a double-blind controlled trial of colchicine in patients with primary biliary cirrhosis. Fifty-seven patients with biopsy-proven primary biliary cirrhosis were randomized to receive either 0.6 mg of colchicine twice daily or an identically appearing placebo. Patients underwent clinical and laboratory evaluation every 3 mo and liver biopsy annually. Differences in mean alkaline phosphatase and alanine aminotransferase values between the colchicine and placebo recipients were statistically significant at 4 yr. Differences in mean bilirubin and immunoglobulin M values, although lower in the colchicine group, did not reach statistical significance. In colchicine-treated patients, mean alkaline phosphatase values fell significantly compared with controls, from 281 to 112 IU/L (p less than 0.01). Similarly, mean alanine aminotransferase values fell significantly compared with controls, from 129 to 86 IU/L (p less than 0.05). Bilirubin values remained stable in drug-treated patients, even in those patients with initially elevated bilirubin values, whereas they nearly doubled in subjects receiving placebo. Although biochemical parameters of disease activity improved or stabilized in colchicine-treated subjects, no difference in histologic progression was detected between the two treatment groups. We conclude that colchicine is of clinical benefit to patients with primary biliary cirrhosis as judged by improvement in alkaline phosphatase and alanine aminotransferase activities as well as a tendency for stabilization of bilirubin values.