This method provides information on health hazard likely to arise from exposure to test substance via oral administration. The method is based on the repeated oral administration of the substance of interest during one limited period (one dose level daily during 28 days). This Guideline is intended primarily for use with rodents (rat preferably). At least 10 animals (5 female and 5 male) should be used for each dose level. Three tests groups, at least, should be used. The test compound is administered by gavage or via the diet or drinking water. A limit test may be performed if no effects would be expected at a dose of 1000 mg/kg bw/d. The report of this study will include results from clinical and functional observations, body weight and food/water consumption measurements, hematology and clinical biochemistry; as well as gross necropsy and histopathology.