The effect of quaternary chlorpromazines like-methiodide, allylammonium chloride, -octylammonium iodide, benzylammonium chloride, -phenacylammonium bromide, 9-phenanthryl-methylammonium bromide, trimethylene-bis-chlorpromazine-ammonium bromide and among the ring-substituted derivatives the 7-hydroxy-, 7,8-dihydroxy-, 7,8-dioxo-, 6,9-dihydroxy-, 6,9-dioxo-chlorpromazines and the chlorpromazine-5-oxide on the prolongation of survival time of NK/Ly ascites tumor bearing mice was studied. The intraperitoneally administered quaternary chlorpromazine derivatives in 10-25 mg/kg daily dose did not increase the life span of the animals, and did not prevent the development of the ascites tumor. However some ring system substituted chlorpromazines such as the 7,8-dioxo- and 6,9-dioxo-derivatives markedly increased the survival time of the tumor bearing mice and reduced the ascite volume in 10 mg/kg body weight dose.