This study was performed to evaluate repeated-dose toxicities of CONP01 in Sprague-Dawley rats. CONP01, a new antiarthritic agent was administered orally to rats at dose levels of 0, 125, 500 and 2,000 mg/kg/day for 4 weeks. In present study, there were no dose response changes in mortality, clinical signs, body weight changes, food and water consumption, ophthalmoscopy, organ weights, urine analysis, hematological findings, and biochemical examination of all animals treated with CONP01. Gross and histopathological findings revealed no evidence of specific toxicity related to CONP01. These result suggest that no observed adverse effect level (NOAEL) of CONP01 may be over 2,000 mg/kg in rats.