A total of 129 transtracheal aspirations or fine needle aspirations, or both, were performed in 65 heart and heart-lung transplant patients to identify the causative pathogen in suspected pulmonary infection. Transtracheal aspiration was performed in 82 instances, fine needle aspiration in 47, and both procedures in 23. Both transtracheal and fine needle aspiration were highly specific, 96% and 100%, respectively. Sensitivity for transtracheal aspiration was lower than for fine needle aspiration, 70% and 89%, respectively. The lower sensitivity of transtracheal aspiration is attributed to its performance in all patients with suspected infection regardless of chest radiographic findings. Fine needle aspiration was performed when identifiable lesions could be used as a "target." Overall accuracy of transtracheal aspiration was 78% compared to 91% for fine needle aspiration both alone and combined with transtracheal aspiration. More invasive procedures such as bronchoalveolar lavage and open lung biopsy were required in only three patients (2%). Transtracheal aspiration resulted in one minor complication (1%). The commonest complication of fine needle aspiration was pneumothorax (21%). There were no deaths associated with either procedure. We conclude that in heart and heart-lung transplant patients with suspected pulmonary infection, transtracheal aspiration and fine needle aspiration are safe and accurate methods to identify the causative organism. More invasive techniques may be required in a small minority of patients.