The present study was carried out to investigate the chemical analysis of Ocimum sanctum for different active compounds, and prepare methanolic and hexane extracts to determine their antimicrobial activity (in vitro). The cytogenetic effects of (methanolic and hexane extracts) as well as methotrexate (MTX) was evaluated in albino male mice (in vivo). The cytogenetic analyses were extended to include mitotic index and chromosomal aberrations. The study also tried to investigate the role of O. sanctum methanolic and hexane extracts in reducing the activity of albino mice sperms morphology. The antimicrobial effects of plant extracts were nvestigated on different types of microorganisms (Staphylococcus aureas, Pseudomonas aeruginosa and Candida albicans), the tested concentrations of methanolic and hexane extracts were 75, 37.5 and 18.75 mg/ml. Results showed that methanolic extract had a good effect on Candida albicans and slight effect on Staphylococcus aureas at three concentrations used, while hexane extract showed there was no effect on tested microorganisms. The cytogenetic effects of plant extract were investigated after seven days of treatment mice with three doses of MTX, the doses were 0.6, 0.8 and 1 mg/kg, while doses of O. sanctum were 200, 400, and 600 mg/kg. The following results were obtained: 1. Chemical analyses showed that O. sanctum methanolic leaves extract contain flavonoids. 2. Chemical analyses showed that O. sanctum hexane leaves extract contain steroids. 40 3. Methotrexate revealed clear effects in reducing mitotic index and increased chromosomal aberrations in mouse bone marrow cells. 4. The inductions in abnormalities of sperm morphology were observed in MTX treatment especially after 35 days of treatment. 5. Methanolic extract of O. sanctum exhibited an increase in mitotic index and decrease in chromosomal abbrations, while hexane extract has no effects. 6. Treatment with O. sanctum methanolic extract results in increasing of malformation of sperm morphology like the formation of amorphous head and coiled tail especially after 35 days of treatment, while hexane extract has no effects.