White sesame seeds, used as an oilseed since ancient time, contain 25% protein and 50% oil, the latter have unique chemical and physiological activities. In view of its important biological activity, this study was performed to evaluate the efficacy of sesame oil (SO) to protect mice against vincristine (VCR) induced genotoxicity using different endpoints. Chromosomal aberrations (CAs) in bone marrow cells and in spermatocytes as well as morphological sperm abnormalities were determined in the tested animals. Mice were orally treated (using a stomach tube) with SO for 7 consecutive days. Vincristine was used as a mutagenic agent and was given intraperitoneally at a single dose of 0.5 mg/kg b.w, 24 hr after last dose of SO. The results clearly showed that SO tested at high dose (400 mg/mouse) didn't induce any genotoxic effect. Pretreatment with the three tested doses of SO (100,300 and 400 mg/mouse) to VCR-treated mice significantly minimized CAs in bone marrow cells and spermatocytes. Morphological sperm abnormalities decreased significantly after treatment with SO. It could be concluded that, intake of dietary SO may be considered a promising approach toward reducing the genotoxicity induced by chemotherapeutic agent VCR. Accordingly, sesame seeds and its components may be exploited commercially for pharmaceutical purposes.White sesame seeds, used as an oilseed since ancient time, contain 25% protein and 50% oil, the latter have unique chemical and physiological activities. In view of its important biological activity, this study was performed to evaluate the efficacy of sesame oil (SO) to protect mice against vincristine (VCR) induced genotoxicity using different endpoints. Chromosomal aberrations (CAs) in bone marrow cells and in spermatocytes as well as morphological sperm abnormalities were determined in the tested animals. Mice were orally treated (using a stomach tube) with SO for 7 consecutive days. Vincristine was used as a mutagenic agent and was given intraperitoneally at a single dose of 0.5 mg/kg b.w, 24 hr after last dose of SO. The results clearly showed that SO tested at high dose (400 mg/mouse) didn't induce any genotoxic effect. Pretreatment with the three tested doses of SO (100,300 and 400 mg/mouse) to VCR-treated mice significantly minimized CAs in bone marrow cells and spermatocytes. Morphological sperm abnormalities decreased significantly after treatment with SO. It could be concluded that, intake of dietary SO may be considered a promising approach toward reducing the genotoxicity induced by chemotherapeutic agent VCR. Accordingly, sesame seeds and its components may be exploited commercially for pharmaceutical purposes.Avaliação de atividade antigenotoxica de extrato de gergelim branco (Sesamumindicum) versus a genotoxicidade induzida por vincristina em camundongosResumoSementes de gergelim branco, usado como uma oleaginosa desde os tempos antigos, contêm 25%de proteína e óleo de 50%, este último tem química única e atividades fisiológicas. Considerandosetendo em vista a sua actividade biológica importante, este estudo foi realizado para avaliar aeficácia de óleo de gergelim (SO) para proteger camundongos contra a genotoxicidade induzidavincristina (VCR) utilizando parâmetros diferentes. Aberrações cromossômicas (CAs) em célulasda medula óssea e em espermatócitos, assim como anormalidades no esperma morfológicasforam determinadas nos animais testados. Camundongos foram tratados por via oral (utilizandoum tubo estomacal) com SO durante 7 dias consecutivos. Vincristina foi usada como um agentemutagênico e foi dado intraperitonealmente com uma dose única de 0,5 mg/kg de peso corporal,24 horas após a última dose de SO. Os resultados mostraram claramente que SO testados emalta dose (400 mg/rato) não induziu qualquer efeito genotóxico. Pré-tratamento com as três dosestestadas de SO (100,300 e 400 mg/rato) para VCR camundongos tratados significativamenteminimizado CAs em células de medula óssea e de espermatócitos. Anormalidades morfológicas deespermatozóides diminuiu significativamente após o tratamento com SO. Poderia-se concluir que,a ingestão dietética de SO pode ser considerada uma abordagem promissora para a redução dagenotoxicidade induzida por quimioterápicos agente VCR. Assim, sementes de gergelim e os seuscomponentes podem ser exploradas comercialmente para fins farmacêuticos.