We report the case of a patient with nausea, loss of appetite and increase of the aminotransferase levels to eight times the upper normal limit occurring two weeks after she was started on isoniazide, rifampicine and pyrazinamide for treatment of tuberculosis. Isoniazide is the most likely cause of liver injury occurring during combined antituberculosis therapy, whereas pyrazinamide or rifampicine are only rarely responsible. The case presented is used to review and compare the different recommendations concerning the monitoring of patients receiving antituberculous therapy and the clinical management of patients developing liver injury.