Population-based case-control interview studies of 622 White men with non-Hodgkin's lymphoma and 820 controls from Iowa and Minnesota (United States) and 173 White men with multiple myeloma and 452 controls from Iowa offered the opportunity to investigate the relationship of these cancers with smoking. Risks were significantly elevated for all lymphoma (odds ratio [OR] = 1.4), high-grade lymphoma (OR = 2.3), and unclassified lymphoma (OR = 2.8) for cigarette smokers. Dose-response gradients were not seen with intensity of cigarette use, but risks for these subtypes were greatest for cigarette smokers of longest duration. Similar elevations in risks were seen for tobacco users. The risk of multiple myeloma was not significantly elevated for either tobacco users or cigarette smokers. The findings from this study confirm the lack of an association between smoking and multiple myeloma and provide some support for an association between tobacco use and certain subtypes of non-Hodgkin's lymphoma.