The inhibitory effect of 108 4, 6-diamino-1, 2-d~ y~~ 2, 2-dimethyl-l-(substitu~ d-phenyl)-s- tri~ ines on murine L5178Y tumor cells, resistant and sensitive to methotrexate (MTX), has been studied. From the pIm values, quantitative structureactivity relationships have been formulated which show that the lipophilic triazines are much more inhibitory against resistant cells than methotrexate or hydrophilic triazines. The results are compared with the ...