The bio-elimination and organ retention of orally administered [14C]benzanthrone, an anthraquinone dye intermediate, were determined in control and ascorbic acid-supplemented guinea pigs. Urinary excretion of benzanthrone in control and ascorbic acid-treated animals during 96 hr was 27.9 and 30.5%, respectively, with peak elimination at 48 hr. Faecal elimination in control and supplemented animals during 96 hr was 24.5 and 38.8%, respectively, with a peak at 48 hr. The organ retention of radiolabelled benzanthrone at the end of 96 hr was of the order of 39% in control animals (gastro-intestinal tract 16%; liver 22%; testis 1.2%); ascorbic acid supplementation reduced benzanthrone retention to 19.5% (gastro-intestinal tract 12.7%; liver 6.8%). Overall, pretreatment of guinea pigs with ascorbic acid caused a 32% enhancement in the clearance of radiolabelled benzanthrone through the urine and faeces, while organ retention was reduced by about 50%. A prophylactic dose of ascorbic acid may prevent benzanthrone-induced toxic symptoms in exposed workers.