1) Data collection has been completed in a collaborative study of lung cancer and residential radon exposure involving 1474 lung cancer cases and 1811 controls. Radon measurements were made in past and current homes of participants using year-long alpha-track etch detectors to estimate cumulative exposure since age 25. Efforts have focused on preparing data for analysis, evaluating methods for imputing missing data, and identifying factors associated with high radon levels. We have demonstrated that using strata-specific mean radon levels generated from measured control homes to impute missing radon values will allow for unbiased estimation of risk with virtually no power loss. We are using linear regression and regression tree analysis to identify meaningful strata with similar radon exposure. Factors that have been found to predict radon include age of residence, relationship of measured level to ground (e.g. below or above ground), radon potential, house type (single family or other), forced air heat, well water, and smokers in the home. 2) We have analyzed data from our study of childhood leukemia risk associated with residential radon. There was no overall association between radon and risk for childhood leukemia among 194 cases and 255 controls studied. However, a slight association with higher radon levels was apparent among cases diagnosed between ages 2 and 10 that is being explored further analysis. 3) Vital status has been determined for more than 95% of our cohort of 18,000 uranium miners from the Czech Republic and linkage with cancer registries is nearly complete. Analysis of death certificates from the Pribram mining region (representing the majority of the miners) suggests a significant increase in risk for laryngeal cancer mortality among miners in addition to the well-documented risk for lung cancer. Preliminary analysis of data on cancer incidence since 1976 also shows increased risks for cancer of the larynx, digestive cancers, and leukemia, risks that have been less apparent in mortality studies.