Several studies have documented a relevant prognostic role of microvessel count (MC) in non-small-cell lung carcinomas (NSCLC). However, no evidence has been reported about the involvement of neo-angiogenesis in the development of bronchial cancers. The aim of this study was to analyze microvessel density both in normal and in pathological features of the bronchial tree detected concomitantly with carcinomas. In a group of 34 patients resected for NSCLC, 48 bronchial lesions (hyperplasia, squamous metaplasia, moderate dysplasia and in situ carcinoma) were identified. In addition, 20 samples of normal bronchial epithelium from the same patients were analyzed. A monoclonal antibody was used in order to identify microvessels in the most intense areas of neovascularization from the bronchial specimens. MC was also analyzed in invasive components. An increased number of microvessels was observed from normal to dysplastic epithelium, including in situ carcinoma. Mean MC was significantly lower in normal, hyperplastic and squamous metaplastic epithelium than in dysplastic epithelium and in situ carcinoma. In particular, no differences were observed between normal and hyperplastic/metaplastic components, whereas a statistically significant difference appeared between the latter and dysplastic lesions. Moderate dysplasia and in situ carcinoma showed a number of microvessels in the lamina propria of their mucosa which were not significantly different from the invasive component, whereas hyperplastic/metaplastic lesions presented a much lower number of microvessels than invasive cancer. From these data it appears that normal bronchial epithelium and lesions associated with cancers of the bronchial tree show neovascularization in their stromal component. Hyperplasia and squamous metaplasia, unlike dysplasia and in situ carcinoma, show a low microvessel count, and they cannot represent precursor or incipient changes in the bronchial epithelium before the fully developed in situ stage has also been reached.