1. New quantitative assays of 6-aminochrysene by spectrophotometric and g.l.c. methods and t.l.c. separation systems are described. 2. The decline in blood levels of the antitumoral agent 6-aminochrysene was due to its distribution rather than to metabolism to polar metabolites, during liver perfusion experiments. 3. No marked changes in kinetics of 6-aminochrysene were observed during perfusion of livers isolated both from normal and from Walker 256 carcinosarcoma-bearing rats.