Fundamental conditions suitable for the cultivation of MN-lymphosarcoma cell were assayed and the results were presented as follow : 1) Static cultere was a more suitable method than roller tube cultere. 2) The cultere in initial pH 7.6 was found to be optimal. 3) Continuous cell multiplication was obtained with the inoculum size of over 100,000 nuclei/ml/tube. 4) 0.4% Lactalbumin hydrolysate in the medium was found to be optimal. 5) The optimal concentration of yeast extract was determined as 0.08% in the medium. 6) Vigorous propagation of the cells was obtained with a medium containing 40% bovine serum. 7) The cell multiplication was not sustained in the medium in whish dialysed bovine serum was substituted for nondialysed one. 8) The cell growth was accelerated markedly in the medium supplemented with dialysed bovine serum after the addition of hexestrol, a synthetic estrogen, to it.