Piperine is a major pungent substance and active component of black pepper (Piper nigrum Linn.) and longpepper (Piper longum Linn.). Both plants are used worldwide as household spices and condiments. They arealso used as important ingredients in folklore medicine in many Asian countries. Therefore, it is of interest tostudy antimutagenic effects of piperine. In this study, its influence on chromosomes was investigated in rat bonemarrow cells. Male Wistar rats were orally administered piperine at the doses of 100, 400 and 800 mg/kg bodyweight for 24 hours then challenged with cyclophosphamide at a dose of 50 mg/kg body weight by intraperitonealinjection. Twenty-four hours thereafter , all animals were sacrificed and bone marrow samples were collectedfor chromosomal analysis. The results demonstrated that piperine at a dose of 100 mg/kg body weight gave astatistically significant reduction in cyclophosphamide-induced chromosomal aberrations. In conclusion, piperinemay have antimutagenic potential. The underlying molecular mechanisms now require attention.