ExperimentaI cigarettes from tobaccos varying in genotype, nitrogen nutrition, stalk position, suckering practice, and curing methods were used to examine the Ievels of N-dimethylnitrosamine (DMN) in smoke. Measurable amounts of DMN were found in all experimental samples, ranging from 1.7 to 115 ng per gram of tobacco burned. DMN content in smoke generally increased as rate of N fertilization increased. However, there were wide seasonal, cultural, and varietal effects. Burley-type tobacco produced a much higher level of DMN than the bright-type tobacco. DMN content in smoke was significantly and positively related to Ieaf total N, totaI alkaloids, nicotine, nornicotine, total volatile bases and nitrate N, but negatively related to reducing sugars. Reconstituted sheet tobaccos made with homogenized-leaf-curing samples produced much lower amounts of DMN than conventionally cured leaf. Additional information is needed to elucidate the primary leaf constituents that serve as precursors of DMN.