Treatment for Mycobacterium tuberculosis has to be lengthy, since populations of this bacillus differ in metabolic activity, and it has to consist of various associated drugs, since spontaneous chromosome mutations can give rise to drug resistance. The multiresistant phenotype emerges with sequential acquisition of mutations in several loci of separate genes. Knowledge of the mechanisms of resistance permits the development of molecular techniques for the early detection of resistant strains, thereby making proper control possible. Tuberculosis treatment includes isoniazid, rifampicin and pyrazinamide during the first two months and isoniazid and rifampicin to complete six months of treatment. In specific situations, a fourth drug is added, ethambutol for adults and streptomycin for children in whom visual acuity cannot be monitored. This review describes the characteristics, activity, resistance mechanisms and side effects associated with the various antituberculosis drugs.