The aim of this paper is to critically review the performance of several published methods for the determination of nicotine in environmental tobacco smoke. The efficiency of liquid absorption decreased with increasing sampling duration. The collection efficiency of both the filter and the Tenax Cartridge of the thermal desorption method diminished with increasing sampling volume due to stripping of the nicotine. The study showed that nicotine collected by simple mechanical filtration always represented an important part of the total nicotine measured. Increasing sampling volume reduced the observed level of nicotine in the particulate phase collected by filtration. Similarly the vapour phase nicotine collected on the treated filter was reduced with increasing sample volume. Most authors, except Neurath, agree that nicotine in environmental tobacco smoke is in the vapour form. This study demonstrates the limitation of published methods and indicates that the level of particular phase nicotine is important. Moreover the proportion of nicotine residing in the particulate and vapour phases changes with the age of the smoke.