Twenty-nine patients with peripheral intrathoracic lesions underwent real-time US and US-guided biopsy. The lesions were mainly atypical fluid collections in 3 patients and mainly solid in the extant 26. Biopsies performed with fine aspirating or cutting needles (20-22 gauge) were successful in all patients; an unquestionable diagnosis was made in 27 cases with cytology and/or histology. Only one patient experienced mild asymptomatic pneumothorax after biopsy, which did not require chest-tube drainage. The authors stress the important diagnostic role of US-guided fine-needle biopsy as an useful and safe method for the evaluation of peripheral intrathoracic lesions.