INTRODUCTION: Clinical characteristics and risk factors of nonsmoker patients with lung cancer are still debated. AIM AND METHODS: The aim of this work is to describe the characteristics of never smoker patients with lung cancer, focusing on occupational and environmental exposures, Data collected were: age, gender, histological types, methods of diagnosis, TNM staging, smoking, and occupational data. Statistical analysis included descriptive analyses, Pearson's chi-square or nonparametric tests, and logistic regressions. RESULTS: All lung cancers diagnosed between January 1, 1997 and December 31, 2006, representing 1493 cases were included. Lung adenocarcinoma (ADC) [Odds Ratio (OR)=2.5 (1.5-4.3), p<0.0001] as well as clinical stage I cases at diagnosis [OR=2.4 (1.3-4.3)] were most frequent in nonsmokers relative to ever smokers. Comparison of clinical features among male and female nonsmoker patients did not reveal significant differences. Conversely, strong differences appeared when comparing environmental tobacco smoke (ETS) and occupational exposures in nonsmoker women vs men: ETS exposure (78.6% nonsmoker women vs 21.4% nonsmoker men, p<0.0001), occupational exposure (9.4% vs 48.6%, p<0.0005). Noteworthy, a sizeable number of nonsmoker male (40.0%), and nonsmoker female (31.2%) patients had no known exposure to major lung carcinogens. CONCLUSIONS: Main risk factors (ETS and occupational exposure) may only explain some cases.