Renal cell carcinoma (RCC) accounts for approximately 3% of adult malignancies. For stage I - III RCC surgery is the primary treatment. Systemic therapy is used in the patients with disseminated disease (stage IV). Sunitinib malate is commonly used in the patients with clear cell renal cell carcinoma (ccRCC) rated as 'low' or 'intermediate' risk according to the Motzer scale. Treatment with sunitinib malate is associated with myelotoxicity. To assess its clinical significance we conducted a pilot study in a group of 10 patients. We noticed a gradual decrease in the mean haemoglobin level during subsequent treatment cycles. Alternations in the platelet count were of no clinical significance. Episodes of the neutropenia were noticed in the study group. In some patients neutrophil count decreased to the level that put them at risk of the infectious complications.