During the time period January 1989-December 1992, a case-control study involving 476 cases of lung cancer and 561 controls was carried out at the Instituto Nacional de Oncología, Montevideo, Uruguay, in order to analyze the patterns of risk of the different cell types of lung cancer, associated with smoking manufactured and hand-rolled cigarettes. Lifelong smokers of hand-rolled cigarettes displayed a non-significant 30% increased risk, compared with smokers of commercial cigarettes, for all types of lung cancer combined. The analysis for cell-type disclosed a fourfold increase in the risk of small cell lung carcinoma associated with lifelong smoking of hand-rolled products. The possibilities of a chance finding and of misclassification of the disease appears to be an unlikely explanation of this strong and rather specific association.