A crossover study with and without food intake in patients with normal renal and hepatobiliary status showed food to render a retarded absorption, lower mean peak levels and longer serum half-lives of josamycin. In patients with biliary occlusion, the elimination of josamycin was markedly slower. Patients with parenchymatous liver disease exhibited intermediate serum half-lives showing a moderate influence on the excretion of josamycin. Since previous studies have shown insignificant amounts to be excreted in the urine, this indicates that the main route of excretion for josamycin is via the hepatobiliary system.