Sirolimus is a potent immunosuppressive drug that began to be used in the last few years. This drug was initially used in renal transplantation but its use in other solid organ transplantations such as liver, heart, lung and pancreas, has been increasing. Sirolimus is indicated in rescue therapies and to reduce the secondary toxic effects of calcineurin inhibitors. However, this drug has been associated with infrequent but severe pulmonary toxicity and cases of interstitial pneumonitis, bronchiolitis obliterans with organizing pneumonia, and alveolar proteinosis have been described. We present the case of a male liver transplant recipient who developed interstitial pneumonitis associated with sirolimus use.