Madakku karisalai thylam (MKT) is a herbal siddha medicine which is used especially for lung diseases. This study was performed to analyze the acute (72hrs) and subacute toxicity (28 days) in wistar rats. The studies were carried out as per the OECD guidelines. In acute oral toxicity, wistar rats were administered a single dose of MKT (2000 mg/kg) orally. The clinical signs, behaviour, body weight and mortality were observed for 14 days. In subacute toxicity study, the wistar rats were administered with MKT for once daily up to 28 days. Clinical signs, body weight, feed, water consumption, haematology, serology, histo-pathology, organ weight were observed. In administration of MKT there was no death or signs of toxicity developed in wistar rats at the dose of 2000 mg/kg b.wt throughout the study period. No gross pathological changes have been seen in the internal organs of both control and treatment group. This study validate MKT is safe for therapeutic dosage.