Scanning electron microscopic studies revealed that ascites Dalton's lymphoma cells are distributed singly (25–30%) or in groups of 2–3 cells (55–60%) and 5 or more cells (10–15%) connected together. The percentage of single cells and groups of 2–3 or more cells changes with tumor growth. The number of single cells is maximal 72 h after tumor transplantation. Control tumor cells revealed the presence of blebs—ruffles all over the cells. Cisplatin treatment of the cellsin vivobrings about definite changes in the arrangement of blebs—ruffles over the cells. At the later stages of cisplatin treatment disintegration and breaking of the plasma membrane occurs, which ultimately results in the lysis of tumor cells.