A prospective study of different side-effects and toxicity of different antituberculosis drugs was made on 125 cases of pulmonary tuberculosis, divided into 3 groups according to the regime of treatment. Group A consisted of 50 patients, taking streptomycin, ethambutol and isoniazid. Group B of 50 patients received streptomycin plus ethambutol plus isoniazid and rifampicin and 25 patients comprising group C received streptomycin plus isoniazid plus ethambutol and pyrazinamide. The group B showed hepatotoxicity in 30% cases, out of which clinical jaundice with abnormal liver function tests being 26% and rest 4% cases were of anicteric hepatitis, while group A showed only 6% hepatotoxicity with 4% clinical jaundice and 2% anicteric hepatitis. In group A out of 50 cases only 2 patients complained of colour blindness, which reversed with the stoppage of drugs. In group C out of 25 cases 3 patients had gouty problems and responded with stoppage of drugs. Patients in group A developed jaundice in a mean of 50 days while those in group B developed jaundice in 17 days.