The incidence of tuberculosis among transplant recipients is greater than in the general population. Mycophenolate mofetil (MMF) is a potent immunosuppressive agent that has become part of most standard immunosuppressive protocols after renal transplantation. We have recently shown that conversion from azathioprine (AZA) to MMF in patients with chronic allograft dysfunction may be beneficial. Here, we report a patient with a history of pulmonary tuberculosis during his childhood. This patient was converted from AZA to MMF therapy 16 years after allogenic renal transplantation because of chronic allograft dysfunction. Two months later, he developed axillary lymph node tuberculosis caused by Mycobacterium tuberculosis. Because he denied contact with infectious persons, we diagnosed reactivation of old dormant tuberculosis. After surgical extirpation, quadruple antituberculous therapy was administered for 3 months (isoniazid, rifampicin, ethambutol, and pyrazinamide), followed by dual therapy for 3 months (isoniazid and rifampicin), and monotherapy for another 3 months (isoniazid). In the follow-up period, he remained asymptomatic with stable graft function. We conclude that MMF therapy in renal allograft recipients may cause reactivation of old dormant tuberculosis, even in the very late posttransplantation period. In these patients, close monitoring and isoniazid prophylaxis may be useful.