The recent publication of the FDA’s HPHC list suggests that reporting of the hydrazine content of mainstream smoke will eventually be required. This paper describes method development challenges, such as potential loss of hydrazine through interactions with other smoke constituents (e.g. volatile carbonyls). The mainstream smoke of cigarettes was passed through a glass fiber filter pad followed by a trap containing 40mL of an aqueous buffer:methanol (55:45, v/v) solution, with 2-nitrobenzaldehyde (10 g/L) used as a derivatizing agent and 15N2-hydrazine used as internal standard. After smoking, the filter pad was extracted with the trapping solution then incubated for 30 minutes at 35°C. An aliquot of the extract was centrifuged and the resultant hydrazone was quantified by liquid chromatography tandem mass spectrometry (LC-MS/MS). Two transitions were monitored for both the hydrazone and the internal standard, with the more abundant transitions used for quantification. This LC-MS/MS method demonstrated good linearity (R2 > 0.999) from 0.079 to 248 ng/mL, with a limit of quantification in mainstream smoke of 0.2 and 0.4 ng/cig for ISO and Canadian Intense smoking regimens respectively. The method recovery was assessed using samples spiked with known amounts of hydrazine. The results showed good accuracy with recovery percentage values ranging from 98 to 111%. Although there were no detectable levels of hydrazine in the reference cigarettes used in the validation (KR3R4F), the method precision was estimated to be approximately 10% based on the variability of spiked samples. Trapping efficiencies were assessed using a hydrazine permeation tube which provided a known amount of hydrazine.