Abstract Krebs-2 ascites carcinoma cells suspended in modified Hanks' salt solution were exposed aerobically for a three-hour period of incubation at 37° C. to low concentrations (2.5 to 10 μg. per ml.) of 5-imino-1,2,4-dithiazolidin-3-thione (IDT), the 5-acetyl derivative of the latter, and bis(diethylthiocarbamoyl)disulfide (antabuse). Cell injury as evidenced by bleb formation was observed with IDT and antabuse; in addition, the latter at 10 μg./ml. caused 100 per cent loss of viability as indicated by the eosin staining technique. Cell injury by the two agents was not evident when they were tested in the presence of reduced glutathione or of glucose.