Abstract: Para-aminosalicylic acid (INN aminosalicylic acid; PAS) is a bacteriostatic chemotherapeutic agent used in the therapy of all forms of tuberculosis, both pulmonary and extrapulmonary, caused by sensitive strains of the mycobacteria resistant to other antituberculotics or if the patient is intolerant towards other drugs. Since its clinical introduction in the late 1940s aminosalicylic acid (PAS) has been a mainstay in the treatment of TB into the 1960s. Along with isoniazid and streptomycin, it was a ‘first-line’ agent for tuberculosis. However, it was plagued by poor gastro-intestinal tolerance and rare but severe allergic reactions. Ethambutol was later shown to be approximately equivalent to PAS in potency, and generally better tolerated than PAS when ethambutol was used at dosages of 25 mg/kg/day or less. Therefore, PAS was replaced by ethambutol as a primary TB drug. However, because of the relative lack of use of PAS over the past 3 decades, most isolates of TB remain susceptible to it. Thus, PAS has experienced a renaissance in the management of patients with multi-drug resistant tuberculosis.