A project having the objective to evaluate tobaccos suitable for smokeless products was initiated in 1989. In the course of this project, a broad range of genotypes was grown under a regimen of heavy nitrogen fertilization (250 lbs N/A) near Reidsville, NC, USA. All tobaccos were air-cured and evaluated with respect to selected physical, chemical and sensory characteristics. The chemical measurements included levels of nicotine, sugar, nitrate, nitrite, and tobacco-specific nitrosamines (TSNA). This presentation will deal with the results obtained with respect to tobacco genotype and TSNA formation. Our results confirm previous findings that bright tobacco varieties tend to have lower levels of TSNA than burley and dark tobaccos after air-curing. In addition, we observed that the TSNA levels are, in general, lower in bright genotypes than in cigar and other traditionally air-cured varieties and in Oriental varieties. Experiments have also been conducted to study the effects of fertilization level, type of fertilizer, and fertilization scheme on the formation of TSNA. The results obtained will be presented. Factors that are likely to influence the formation of TSNA in a given tobacco will be discussed. These include levels of precursors, i.e . alkaloids and nitrosating species, levels of potential inhibitors and relative rate of moisture loss from the tobacco leaf during air-curing.