Background: This research evaluated the genotoxicity of oil and tincture of H. annuus L. seeds using the micronucleus assay in bone marrow of mice. The interaction between these preparations and the genotoxic effects of doxorubicin (DXR) was also analysed (antigenotoxicity test). Methods: Experimental groups were evaluated at 24-48 h post treatment with N-Nitroso-N-ethylurea (positive control - NEU), DXR (chemotherapeutic), NaCl (negative control), a sunflower tincture (THALS) and two sources of sunflower oils (POHALS and FOHALS). Antigenotoxic assays were carried out using the sunflower tincture and oils separately and in combination with NUE or DXR. Results: For THALS, analysis of the MNPCEs showed no significant differences between treatment doses (250-2,000 mg.Kg(-1)) and NaCl. A significant reduction in MNPCE was observed when THALS (2,000 mg.Kg(-1)) was administered in combination with DXR (5 mg.Kg(-1)). For POHALS or FOHALS, analysis of the MNPCEs also showed no significant differences between treatment doses (250-2,000 mg.Kg(-1)) and NaCl. However, the combination DXR + POHALS (2,000 mg.Kg(-1)) or DXR + FOHALS (2,000 mg.Kg(-1)) not contributed to the MNPCEs reduction. Conclusions: This research suggests absence of genotoxicity of THALS, dose-, time- and sex-independent, and its combination with DXR can reduce the genotoxic effects of DXR. POHALS and FOHALS also showed absence of genotoxicity, but their association with DXR showed no antigenotoxic effects.14Rede Mineira de Ensaios Toxicologicos e Farmacologicos de Produtos Terapeuticos (REDE MINEIRA TOXIFAR)Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)