The purpose of this study was to investigate the potential subacute toxicity of dimethyl disulfide by 3 weeks inhalation in F344 rats. The test article, dimethyl disulfide was exposed by inhalation to male and female rats at dose levels of 0, 5, 25, or 125 ppm/6 hrs/ day for 3 weeks. Five rats/ sex/ group were sacrificed on day 4 after the initiation of treatment, while 5 rats/ sex/ group were sacrificed at the end of treatment period. During the test period, clinical signs, mortality, body weights, food consumption, hematology, serum biochemistry, and gross findings were examined. Slight decreases in body weight gain were noted in both sexes of the highest dose group in a dose dependent manner but were only statistically different from the control animals in males of the group. A slight non-significant reduction in food consumption were also noted in the both sexes of the highest dose group. There were no adverse effects on mortality, clinical signs, hematology, serum biochemistry, and necropsy findings at any dose tested. Based on these results, it was concluded that the 3 weeks repeated dose of dimethyl disulfide by inhalation resulted in suppressed body weight gain and decreased food consumption at 125 ppm of both sexes. In the present experimental conditions, the target organ was not determined in rats. The no­observed-adverse-effect level (NOAEL) was considered to be 25 ppm/6 hrs/day for both sexes.