Simian virus 40 (SV40) growth on rhesus kidney cells and on the T-22 line of SV40-transformed green monkey kidney (GMK) cells is largely limited by the low plating efficiency of SV40 on these cells. In addition, a fraction of the rhesus kidney and T-22 cells are resistant to infection by SV40. Nevertheless, 72-h viral yields per infected rhesus kidney and T-22 cell are nearly equivalent to that obtained on normal GMK cells and are independent of the multiplicity of infection. Despite the production of high viral yields, infected rhesus kidney and T-22 cells are killed slowly by SV40. Monolayers of these cells are also refractory to plaque formation by SV40. SV40 induces the release of lysosomal N-acetyl-beta-glucosaminidase into the cytoplasmic fractions of rhesus kidney and T-22 cells to an extent equal to that observed during infection of rapidly killed normal GMK cells. In contrast, damage to the plasma membrane, as indicated by the release of the cellular enzymes lactic dehydrogenase and glutamic oxaloacetic transaminase into the overlay media, occurred to a much greater extent in the normal GMK cells than in the rhesus kidney or T-22 cells. Neither a lysosomal hydrolase mechanism nor viral release appear to be responsible for this phenomenon. The different rates and extents of the SV40 cytocidal process on these cells do not result from the differences in the viral plating efficiency on them.