l-Muscone is synthesized for use as substitutive material of musk which is the active ingredient of woohwangchungsimwon. The objective of this investigation was to evaluate the acute and subacute toxicity of l-muscone in rats. In oral acute toxicity test, SPF Sprague-Dawley male and female rats were gayaged with l-muscone of two doses(0, 5.0 g/kg). No dead animal and abnormal autopsy findings were found in control and treated group. Body weights were slightly decreased in both sexes of rats treated with 5.0 g/kg. Therefore, oral $LD_{50}$ of l-muscone was consider to be higher than 5.0 g/kg in male and female rats. In intraperitoneal acute toxicity test, rats were injected intraperitoneally with dosages of 0, 1,000, 1,316, 1,732, 2,279 and 3.000 mg/kg. Decreased body weights and motor activities were observed at high dose group. Intraperitoneal $LD_{50}$ of l-muscone were 1,920 mg/kg in male and female rats. In the subacute study, l-muscone was administrated orally to both sexes of rats for 4 weeks as several doses(0, 10, 100 and 1,000 mg/kg). There were neither dead animals nor significant changes of body weights during the experimental period. In addition, no differences were found between control and treated groups in clinical signs, urinalysis, hematology, serum biochemical analysist and other findings. Above data suggest that no observed adverse effect level of l-muscone in rats might be over 1,000 mg/kg/day in this study.