The present investigation was carried out to evaluate the safety of methanol extract from leaves of Plectranthus amboinicus (Lour) Spreng by determining its potential toxicity after acute and sub acute administration in mice. For the acute study, PAS was administrated to mice in single doses given by oral route. General behavior adverse effects and mortality were determined up to 7 days. In the Sub acute study, the extract was administered orally at doses of 200 and 400 mg/kg for 28 days to mice. Body weight, biochemical and hematological parameters were determined at the end of 28 days of daily administration. The studies on sub acute toxicity reveals that no mortalities or evidence of adverse effects have been observed in Balb C mice following acute oral administration at the highest dose of 2000mg/kg crude extracts of PAS. In sub acute toxicity study daily oral administration of methanol extract 200 and 400 mg/kg body wt of PAS for up to 28 days did not result in death or significant changes in body weight, hematological and biochemical parameters. Studies on histopathological examination of vital organs showed normal architecture suggesting no morphological disturbances.PAS extract found to be less toxic at the doses examined.