The bacterial flora of the skin from different anatomical sites on cancer patients and a control group of medical personnel was examined. This was done to ascertain if antineoplastic therapy was able to change the pattern of microbial flora of patients and to provide a control for possible infectious complications. The results show that in the control group bacterial flora was normal and the antineoplastic treatment did not succeed in changing the bacterial pattern in the skin of patients deeply. Gram negative bacteria were isolated more frequently from the skin of leukemia patients than from either patients with malignant melanoma or other neoplastic diseases.