Abstract: In order to investigate the effects of smoking parameters on the yields of nitric oxides in mainstream smoke, 10 cigarette samples were smoked under different smoking regimes. The effects of various smoking parameters on the deliveries of nitric oxides per unit nicotine yield were analyzed. The results showed that increasing puff volume and puff frequency always raised the yield of nitric oxides in mainstream smoke. The yield of nitric oxides increased by 1.5-2.5 times when puff volume increased from 35 to 55 mL,while the yield of nitric oxides per unit nicotine yield remained basically unchanged. The yield of nitric oxides increased by 1.5-2 times when puff duration changed from 60 s to 30 s,and the yield of nitric oxides per unit nicotine yield increased as well. The effect of increasing vent hole blocking on the yield of nitric oxides was mixed among cigarette samples, however,the yield of nitric oxides per unit nicotine yield decreased. The yields of nitric oxides in mainstream cigarette smoke under Health Canada smoking regime were significantly higher than those under ISO regime.