β-glucan is a well-known polysaccharide for its chemopreventive effect. This study aimed to evaluate the chemopreventive ability of β-glucan in somatic and germ cells through the dominant lethal and micronucleus assays, and its influence on the reproductive performance of male mice exposed to cyclophosphamide. The results indicate that β-glucan is capable of preventing changes in DNA in both germ cells and somatic ones. Changes in germ cells were evaluated by the dominant lethal assay and showed damage reduction percentages of 46.46% and 43.79% for the doses of 100 and 150 mg/kg. For the somatic changes, evaluated by micronucleus assay in peripheral blood cells in the first week of treatment, damage reduction percentages from 80.63-116.32% were found. In the fifth and sixth weeks, the percentage ranged from 10.20-52.54% and -0.95-62.35%, respectively. Besides the chemopreventive efficiency it appears that the β-glucan, when combined with cyclophosphamide, is able to improve the reproductive performance of males verified by the significant reduction in rates of post-implantation losses and reabsorption in the mating of nulliparous females with males treated with cyclophosphamide.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná (FAADCT/PR)Universidade Federal de Mato Grosso do Sul Núcleo de Hospital Universitário Terapia Celular e Genética ToxicológicaUniversidade Federal de Mato Grosso do Sul Faculdade de Medicina Dr. Hélio MandettaUniversidade Federal de Mato Grosso do Sul Centro de Ciências Biológicas e da SaúdeUniversidade Estadual de Londrina Departamento de Biologia GeralUniversidade Estadual Paulista Júlio de Mesquita Filho Instituto de BiociênciasUniversidade Estadual Paulista Júlio de Mesquita Filho Instituto de Biociências