Studies on the acute pathologic effects of 4-(p-dimethyl

aminostyryl)quinoline (4M20) in mice (3, 10) indicated that the compound had certain radiomimetic effects. It was also noted that lens cataracts occurred in animals surviving the acute effects (5). A striking nonradio mimetic feature of the acute lesions was the marked hepa totoxic effect of the drug. This was manifested by fatty liver and necrosis of liver cells during the 1st week, followed by repair in the second week. Residual liver changes persisted in survivors of the acute toxicity. The fate of such survivors later in life is reported here.