There is continuing interest, by health professionals and individuals, in the composition of mainstream tobacco smoke. Regular official surveys of tar, nicotine and carbon monoxide yields are from time to time supplemented by special surveys of specific components. In this study, gas chromatography-mass spectrometry was used to identify and quantify benzene and certain other volatile compounds of interest in the mainstream smoke of 26 cigarette brands on the UK market and of smoke from hand rolled tobacco. Validation of the method adopted demonstrated the ability to identify and to measure reliably the yields of benzene and seven other compounds: toluene, ethylbenzene, m/p-xylene, o-xylene, styrene, isoprene and acrylonitrile. Yields of these analytes were ranked and compared with the tar yields of the brands. In general terms, brands yielding < or = 3 mg of tar yielded proportionately more of the vapour phase analytes than did brands yielding > 3 mg of tar per cigarette. For many of the higher tar brands the yield of vapour phase analyte was approximately proportional to the tar yield. Smoking cigarettes with an average yield of 50 micron of benzene per cigarette has been compared with the occupational maximum exposure limit (16 mg m-3) concentration and with US studies on the home environment. Smoking the majority of brands examined could contribute significantly to the population exposure of benzene and the other volatile organic compounds considered in this study.