To evaluate the utility of transthoracic needle aspiration biopsy (TTNAB) following negative fiberoptic bronchoscopy (FOB) in a patient with a solitary pulmonary nodule (SPN), we reviewed the records from 262 patients who had undergone TTNAB over an eight-year period. Fifty-eight patients had a SPN and met the criteria for inclusion in this series. Twenty-five of these (43 percent) were diagnosed by TTNAB; 24 had malignant lesions; one had M tuberculosis. Of the remaining 33 patients, 18 went on to definitive diagnostic procedures (surgery, repeat FOB or TTNAB). Nine of these patients had a malignancy. Fifteen patients were followed long-term; one was diagnosed with carcinoma two years after the initial work-up. Carcinoma was not found in any patient under 40 years of age. A benign lesion was diagnosed by TTNAB in only two patients. We conclude that TTNAB is a valuable procedure in the evaluation of patients with a SPN and negative FOB. While a negative FOB and TTNAB do not assure that the lesion is benign, a complex of variables influences the decision regarding thoracotomy vs careful follow-up.