Effective chemotherapy of tuberculosis not only reduces morbidity and mortality, but it is a powerful mechanism to control further spread of infection. Although conventional therapy for 18-24 months is highly effective, a major disadvantage is non-compliance of patients in completing the full course of therapy. With better understanding of bacteriologic action of many antituberculous drugs, the disease can now be cured in six to nine months of bactericidal chemotherapy. Isoniazid and rifampin for nine months, either given daily throughout or initially for one month followed by twice weekly administration for another eight months, is highly effective for cure of the disease. However, this is not recommended for patients in developing countries due to high frequency of initial isoniazid resistance. Bactericidal therapy with four drugs (streptomycin or ethambutol (25 mg/kg), isoniazid, rifampin and pyrazinamide) daily for two months followed by isoniazid and rifampin daily or twice weekly for another four months is very effective. In suspected or proved isoniazid resistance, the therapy has also proven effective. However, therapy may also be changed during the continuation phase to streptomycin, rifampin and pyrazinamide daily or twice weekly for another four to six months. The treatment of extrapulmonary tuberculosis, alone or when associated with other medical disorders, is the same as for pulmonary tuberculosis. There are several short course regimens available for use in developing countries while keeping in consideration the shortage of major drugs and financial constraints. Modern short course chemotherapy has the potential advantage of success in developing countries by increasing the population of patients completing therapy.(ABSTRACT TRUNCATED AT 250 WORDS)