Polyamines excretion with the urine in patients with cancer of the stomach, lung, mammary gland and cervical cancer is considerably increased, as compared with patients having nontumor lesions and healthy individuals. Following a surgical removal of the tumor as well as after chemotherapy the level of polyamines in the diurnal urine is diminished up to normal values. The determination of polyamines excretion may serve as a test for laboratory diagnosis of malignant tumors and also as a criterion of the efficacy of treatment.