The absorption of bismuth from five 205Bi-labelled pharmaceutically used bismuth compounds was studied in man. From single oral doses of all compounds under investigation only less than 0.1% bismuth was absorbed and excreted with the urine. A significantly higher absorption was observed from the colloidal bismuth subcitrate (0.042% of the dose) and the basic bismuth gallate (0.038%) than from the basic bismuth salicylate, nitrate, and aluminate (0.005-0.002%). No retention of bismuth in the whole body was found from the single dose experiment. The biologic fast-term half-lives of absorbed bismuth were calculated to be 0.12 and 1.5 days.