Pulmonary complications after orthotopic liver transplant (OLT) are frequent, involving high morbidity and mortality. We have determined the pulmonary complication incidence in 187 patients submitted to OLT at the General University Hospital "Gregorio Marañón" in the last 4 years, analyzing the type of infection, evolution, diagnostic and therapeutic measures and their influence on OLT mortality. A total of 120 patients had pulmonary complications, the most frequent being pleural effusion (61.94%), pneumonia (43.36%), and pneumothorax (11.5%). Serious pulmonary hypertension was diagnosed by invasive methods in two patients at the time of surgery (unidentified before OLT); both died at early post postoperative times. Pleural effusion was noted in 70 patients, 31.42% of them requiring thoracic tube drainage, complications developing in 22.72%. Thirteen patients were diagnosed of pneumothorax, the most frequent etiologies being percutaneous liver biopsy, thoracic tube drainage for pleural effusion, and postoperative complications in 41.6, 33.3, and 23.3%, respectively. Pneumonia was diagnosed in the 1st month after OLT in 45 patients. Tests to diagnose and identify the etiological agent were made in 71.1% of diagnosed pneumonia patients, identification being obtained in 62.5%. Telescope catheter culture identified the agent in 48%, fiber optic bronchoscopy in 50%, and lung or pleural biopsy in 100%. Respiratory insufficiency was noted in 64 patients (34.22% of transplanted patients). Factors involved in their development were pneumonia (42.18%), graft dysfunction (39.06%, pleural effusion (34.37%), sepsis (28.18%), and poor nutritional status (7.81%). Fifty patients (41.66%) died, pulmonary pathology being the determinant factor in 28.8%. Patient mortality with respiratory insufficiency was greater, especially in those with three factors involved the development of respiratory insufficiency.