Vincristine, an alkaloid of Vinca rosea L. is an effective cytostatic drug. However, apart from properties of which oncologic praxis takes advantage, the drug exerts unfavourable effects on peripheral and central nervous systems. To examine neurotoxic properties of vincristine, the drug was given intraperitoneally to 20 rats of Wistar strain. A single dose amounted to 0.01 mg per kg body weight and was twice as low as the dose used in therapy of humans. The spinal cord was studied. Sections of the cervical, thoracic and lumbar segments were stained according to H + E and Nissl techniques, subjected to Feulgen's reaction and stained according to Einarson's technique to determine level of all nucleic acids. Morphometric, karyometric and cytophotometric studies of neurocytes in anterior horns of the spinal and of oligodendroglia of lateral columns were performed using Morphoquant microscopic image analyzer coupled to a KSR 4100 computer. Results of measurements were compared to those of control animals and significance of alterations was evaluated statistically. Vincristine administration was observed to induce decrease in cross-section size of neurocytes in anterior horns of the spinal cord and decreased nucleic acid extinction, in the cervical and thoracic segments. No changes were noted in cell nucleus size in the cells. Changes observed in oligodendroglia were more pronounced than those seen in neurocytes and included decrease in size, acquisition of a more round and regular shape of nucleus cross-section of the cells associated with a decrease in DNA extinction in the cervical and lumbar segments of the spinal cord.