Cigarette smoke is a source of free radical which possesses a negative impact on reproductive health, especially on sperm quality which effects spermatogenesis process. The aims of this research were to examine the influence of dichloromethane fraction of bawang dayak bulbs on the quality of sperm due to the smoke exposure, to examine the effective dose of dichloromethane fraction of bawang dayak bulbs in preventing the decrease of sperm quality after smoke exposure, and to evaluate difference of antioxidant ability from dichloromethane faction and ethanol extract of bawang dayak bulbs with a dose of 90mg/kg bw after smoke exposure. This study using the completely randomized design with 24 rats as sample were divided into six treatment group of 4 mice each. Smoke exposure was conducted for 30 days. The data consisted of sperm morphology, amount, and sperm viability. The quantitative data was analyzed with ANOVA followed by BTN, whereas the qualitative data was showed in picture. The result showed that the smoke-induced rats treated with dichloromethane fraction of bawang dayak bulbs is determined as an effective dose to prevent the decrease of sperm quality after smoke exposure. Therefore, it can be conclude that the antioxidant ability of dichloromethane fraction of bawang dayak bulbs with a dose of 90 mg/Kg bw after smoke exposure. Keywords: Smoke, antioxidant, onion Dayak, the quality of spermatozoa