Ageratum conyzoides L. (Compositae) is found in many parts of Kenya. The plant is traditionally used for its antispasmodic, haemostatic, antiasthmatic and insecticide activities and for the treatment of wounds and Staphylococcus aureus infections. The present investigation was carried out to evaluate the safety of ethanol extract of Ageratum conyzoides L. (EAC) whole plant by determining its potential toxicity after acute and chronic administration in rats. Study on acute toxicity of extract found to be safe at the doses 2000mg/kg body weight orally as per OECD guidelines No.423. General behavior adverse effects and mortality were determined for up to 14 days. In the chronic toxicity study, the EAC was administered orally at doses of 100, 200 and 400 mg/kg once in a week for 6 weeks to rats. Biochemical and hematological parameters were determined after 6 weeks. In the acute study in rats, there was no toxicity/ death was observed at the dose of 2000mg/kg b.w. The onset of toxicity and signs of toxicity also not there. In the chronic toxicity study, no significant treatment-related changes in the levels of haematological, hepatic and renal parameters such as SGOT, SGPT, cholesterol, creatinine, urea, uric acid, protein and glucose, and serum ALP activities were observed at the termination of the study. It suggests that the ethanol extract of Ageratum conyzoides L. does not appear to have significant toxicity. In view of the dose of Alocassia macrorhiza consumed in traditional medicine, there is a wide margin of safety for the therapeutic use of the ethanol extract of Ageratum conyzoides L. whole plant.