Introduction. Suppression of activation of an alternative immune response is promising approach of tumor immunotherapy. In this study we evaluated antitumor and antimetastatic activity of SNK-411.Objective. Evaluation of antitumor and antimetastatic activity of 5-hydroxypyrimidine derivative SNK-411 in mouse melanoma B16 model.Materials and methods. Antitumor and antimetastatic activity of the SNK-411 were studied in tests on male C57BL/6 mice using the B16-F10 melanoma model. SNK-411 was injected intraperitoneally at doses of 10 and 25 mg/kg from day 2 to day 15 of melanoma development. Doxorubicin was injected at dose of 4 mg/kg on day 2 of tumor development to act as positive control. Antitumor and antimetastatic activity were studied by calculation of tumor growth inhibition and metastasis inhibition index (MII).Results. SNK-411 at doses of 10 and 25 mg/kg and in combination with single injection of doxorubicin in dose of 4 mg/kg showed antimetastatic activity. MII in SNK-411 at 10 mg/kg dose was 72 %, at dose of 25 mg/kg was 82,9 %. The combination of 14-day course of intraperitoneal injections of SNK-411 at dose of 10 mg/kg and injection of doxorubicin 4 mg/kg revealed MII 97,1 %, in half of mice in this group metastasis were not observed on 21st day of melanoma development. All results are statistically significant. There was no significant inhibition of tumor growth in all groups.Conclusion. SNK-411 has antimetastatic activity in tests on melanoma B16 model. Further investigation is required.