The binding of radioactive methylmercuric chloride ([203Hg] -CH3HgCl) with various subcellular fractions of glioma (C-6) and neuroblastoma (NBP2) cells was studied. Confluent cells were incubated in the presence of radioactive CH3HgCl for a period of 5 h, and then various fractions were isolated. Most of the radioactivity was associated with the cytosol and particulate fractions. The cytosol and lipoprotein fractions of glioma cells incorporated more radioactive CH3HgCl than those of NB cells. The specific radioactivities of the particulate, lipid and chromatin fractions were comparable in both cell types. © 1979.