The incidence of venous thromboembolism (VTE) by lung cancer histology and stage is unknown. To determine the incidence of VTE and the risk factors associated with development of VTE in a large population-based study of patients with non-small cell and small cell lung cancer. The California Cancer Registry was merged with the Patient Discharge Data Set to determine the incidence of VTE among lung cancer cases diagnosed between 1993 and 1999. Among 91 933 patients with newly diagnosed lung cancer, the 1-year and 2-year cumulative VTE incidences were 3.0% and 3.4%, respectively, with a person-time rate of 7.2 events/100 patient-years during the first 6 months. The 1-year incidence of VTE was significantly increased in comparison to the general population [standardized incidence ratio = 21.2, 95% confidence interval (CI) = 20.4-22.0]. In a multivariate model, significant predictors of developing VTE within 1 year of non-small cell lung cancer (NSCLC) diagnosis were: younger age, the number of chronic medical comorbidities [hazard ratio (HR) = 2.8 if 3 vs. 0, 95% CI = 2.5-3.1], advancing cancer stage (HR = 4.0 for metastatic vs. local disease, 95% CI = 3.4-4.6) and adenocarcinoma histology (HR = 1.9 vs. squamous cell, 95% CI = 1.7-2.1). In multivariate models, VTE was a significant predictor of death within 2 years for both NSCLC and small cell lung cancer (SCLC), HR = 2.3, 95% CI = 2.2-2.4, and HR = 1.5, 95% CI = 1.3-1.7, respectively. Approximately 3% of lung cancer patients developed VTE within 2 years. The diagnosis of VTE was associated with a higher risk of death within 2 years for NSCLC and SCLC.