Single and 4 weeks oral administration of l-muscone, a major active ingredient of musk, to beagle dogs of both sexes were performed to investigate both acute and subacute toxicity. Beagle dogs(3 males and 3 females) in acute experiments were administered orally with single dosage of 2,000 mg/kg and groups of 9 male and 9 female beagle dogs in subacute experiments were given daily different dosage of l-muscone, 0.2 mg/kg/day(low dosage group), 2 mg/kg/day(middle dosage group), or 20 mg/kg/day(high dosage group) once a day for 4 weeks by oral route according to the Established Regulation of Korean Food and Drug Administration(1996.4.16). $LD_{50}$ value for beagle dogs was more than 2,000 mg/kg on oral route for both male and females. In animals administered with l-muscone, there were neither dead animals nor significant changes of body weights. In addition, no differences were found between control and treated groups in clinical signs, urinalysis, eye examination, hematology, serum chemistry, organ weight and other findings. No histolopathological lesions were observed in both control and treatment groups. Above data strongly suggest that l-muscone in beagle dogs is considered to be safe.