The effect of different Inosiplex doses in tissue culture was studied utilizing a cellular line derived from the Hamster Kidney (BHK). Inosiplex doses used were 0.1, 1, 10 and 100 mg/ml of Eagle basal medium adding 10 per cent of heat inactivated fetal calf serum. Increase in cellular growth that was statistically significant was observed in 10 and 100 microgram/ml Inosiplex doses. Also this substance was studied at same concentrations in other two cellular lines, one derived from loose connective tissue in mice (L-929) and the other from cervical carcinoma (HeLa). In the first, 10 and 100 microgram/ml doses produced growth inhibition while in the second no effect was observed.