Introduction: Initial analyses of the novel smokeless tobacco products Camel Snus and Marlboro Snus demonstrated that these products contain relatively low amounts of nicotine and the carcinogenic tobacco-specific nitrosamines N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), as compared with traditional smokeless products. It is unknown whether the modifications in packaging, flavors, and pouch sizes that occurred for both Camel Snus and Marlboro Snus since their first introduction to the market were accompanied by any changes in nicotine or nitrosamine levels. Methods: We examined the available data on nicotine and NNN and NNK levels in 60 samples of Camel Snus and 87 samples of Marlboro Snus that were analyzed in our laboratory between 2006 and 2010. Results: Due to the increase in pouch size, the amounts of total nicotine, unprotonated nicotine, and the sum of NNN and NNK present in the large Camel Snus pouches released in 2010 are 1.9-fold, 2.4-fold, and 3.3-fold higher, respectively, than in the original smaller pouches that entered the market in 2006. Total and unprotonated nicotine content in the current version of Marlboro Snus pouches are 2.1-fold and 1.9-fold higher, respectively, and the sum of NNN and NNK is 1.5-fold lower than in the original version. Conclusions: We observed an increase in nicotine content in single portions of Camel Snus and Marlboro Snus, and an increase in tobacco-specific N-nitrosamine content in single portions of Camel Snus, due to the increases in pouch size that occurred between 2006 and 2010. This finding stresses the importance of tobacco product regulation and ingredient disclosures.