Bile of guinea-pigs who have received [14C]-histamine contains 14C. 2. Both sexes eliminate in bile about 3.5% of the 14C administered. 3. Histamine metabolites in bile are mainly methylimidazolacetic acid and imidazolacetic acid and its riboside. 4. Acetylhistamine is present in bile. 5. Male bile contains more free histamine and methylhistamine than that of females.