Biliary excretion of arsenic and its distribution in the organism were studied in golden hamsters after administration of Na3(74)AsO3 and Na2H74AsO4 solutions. Significant differences between the two valency forms of arsenic were found in the biliary excretion rate as well as in the cumulative biliary excretion of 74As. The arsenic biliary excretion after treatment with 74AS [III] [4.98 /+- 7.1, or 0.6 [0.2 - 1.1] percents of the administered dose] than that after 74As [V] application. On the other hand, arsenic excretion in the urine and stool were higher after the administration of pentavalent arsenic. The contents of 74As in the liver, kidneys, blood plasma and GIT wall were higher after the application of 74As [III]. It has been again confirmed tha compared to rats the hamster [similarly as the other laboratory animals] exhibits a significantly lower concentration of 74As in red blood cells [differences ranged by 2 orders of magnitude].