Reactivation of tuberculosis is rare in patients receiving chemotherapy for solid tumours, and poorly documented in patients receiving molecular targeted therapy. We report on a patient with metastatic renal-cell carcinoma treated with temsirolimus, who developed respiratory symptoms and mild fever after 6 weeks of treatment. CT-scan and laboratory tests were consistent with reactivation of tuberculosis. The patient received anti-tuberculosis therapy including rifampicin, a potent CYP3A4/5 inducer. After introduction of rifampicin-based treatment, the patient experienced tumour progression, leaving questionable the potential pharmacokinetic interaction between rifampicin and temsirolimus, a substrate for CYP3A4.