The incidence of non-Hodgkin's lymphoma (NHL) has risen dramatically over the past 50 years. In the search for new risk factors, blood transfusions have been investigated and shown to be associated with subsequent lymphoma in some studies. The authors tested this association in a population-based, case-control study conducted between 1988 and 1995 in the San Francisco Bay Area of California. A total of 1,591 histologically confirmed adult cases of NHL were included in this study. Cases were frequency matched to 2,515 control participants by sex, county of residence, and 5-year age intervals. Multivariate logistic regression models were used to examine the impact of possible confounders. Persons who reported a history of allogeneic transfusion were not at increased risk of NHL in this population (odds ratio (OR) = 1.0, 95% confidence interval (CI): 0.84, 1.2). No significant associations were seen when lymphomas were stratified by histologic subtype, grade, or latency period. However, autologous transfusions were associated with a decreased risk (OR = 0.39, 95% CI: 0.16, 0.94). In summary, these findings are similar to those of prior negative studies and do not support some previous reports of an adverse association between blood transfusion and NHL.