A single and repeated doses of DMBA are toxic to immune system. Black cumin seed oil (BCSO) is immunoprotector agent. A study was performed to identify antiimmunitoxicity effects of BCSO on DMBA-induced SD mice. This study was conducted with an experimental design with BCSO administration group and a normal control group. DMBA induction was administered by two methods: a single dose of 15mg/mouse per oral (DMBA15group), and repeated doses of 10 × 20mg/kgb twice/week for 5 weeks (DMBA20/group). Normal control was a non-DMBAinduced group while diseased groups were DMBA-induced groups, DMBA15 and DMBA20. Treatment groups were DMBA 15 and DMBA 20 which were given 0.25ml/kgBCSO 14 days before and during DMBA induction (DMBA15BCSO and DMBA20BCSO groups. Observation was carried out on peripheral blood, spleen histological description and spleen weight, CD4 and CD4CD25 lymphocyte counts. Results showed that the single and repeated doses of DMBA in SD mice are immunosuppressive and hematotoxic. The administration of 0.25ml/kgbwBCSO can decrease the immunosuppressive and hematotoxic effects of DMBA. The number of leukocyte and CD4Th in the treatment groups was higher than the diseased group (p < 0.05). Conclusion: BCSO is the antihematotoxic immunoprotector for diseased groups.