Objective: The diagnosis of pulmonary nodules has become one of the main indications of video-assisted thoracoscopic surgery (VATS), especially for small nodules not accessible by bronchoscopy or by percutaneous transthoracic needle aspiration. In this study we evaluate the indications, diagnostic safety, complications, and technical dif®culty of VATS in the diagnosis of pulmonary nodules in Spain. Materials and methods: We conducted a prospective study of 209 patients with one or more pulmonary nodules from a group of Spanish thoracic surgery divisions (The Spanish Video-assisted Thoracic Surgery Study Group). Data was collected and evaluated on variables contained on a questionnaire including demographic information, characteristics of the nodules, identi®cation methods, surgical technique, morbidity and mortality rates, and diagnostic yield. Results: The mean size of the nodules was 1.9 cm (range 0.3±5 cm). A total of 93.3% were peripheral. A diagnosis was established in 100% of the cases. In this study, 51.1% of lesions were benign and 48.8% were malignant. In 16.3% of cases, a conversion to thoracotomy was needed. The morbidity was 9.6% and the mortality 0.5%. We found a relationship between the size of a nodule and a diagnosis of malignancy (P 0:019) and between a central location and a need to convert to thoracotomy (P 0:002). Patients with nodules .2 cm had a greater risk of complications (P 0:0001). Conclusions: In the diagnosis of pulmonary nodules, VATS has a speci®city of 100% and a low mortality rate. The probability of developing complications is higher when the nodule is . 2 cm. q