The lowering of the TLV for hydrazine by a factor of 10 dictated the need for a new method for air sampling of this chemical. With introducticn of new non-missile applications of hydrazine, the Air Force found a need not only for a method that could be used to determine concentrations less than 0.1 ppm for both long and short term sampling, but also for one that could be readily used for personal exposure monitoring, and one that allowed for field analysis of the collected sample. A method using collection on solid sorbent sampling tubes and analysis by a field colorimetric procedure was developed and proved very satisfactory. The accuracy of this simple and rugged method was well within NIOSH recommendations and the method could be used to determine concentrations well below 0.1 ppm using 1–4 L/min personal sampling pumps for less than 10 minute sampling or 0.05–0.20 L/min pumps for sampling over 3 hours.