Polycyclic aromatic hydrocarbons (PAHs) were measured in mainstream and sidestream tobacco smoke from 14 commercial brands of cigarettes purchased in Italy during 2001–2002. The PAHs detected in smoke and analysed with HPLC and a ﬂuorimetric detector were: ﬂuoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[a]pyrene, benzo[b]ﬂuoranthene, benzo[k]ﬂuoranthene, benzo[g,h,i]perylene and dibenzo[a,h]anthracene. The PAH levels in mainstream smoke from different cigarette brands obtained using an ofﬁcial smoking machine varied by about threefold (from 118 to 374 ng per cigarette for total PAHs and from 23.5 to 100 ng per cigarette for carcinogenic PAHs). Total PAH levels in mainstream smoke were correlated with tar content (r = 0.615, P < 0.05, n = 14). Total PAH content in sidestream smoke, measured by collection of all the smoke produced by a lit cigarette in a glass chamber, was about tenfold higher compared with mainstream smoke. The PAH content in sidestream smoke was relatively uniform (2.3–3.9 and 0.49–1.21 µg per cigarette for total and carcinogenic PAHs, respectively) and was not correlated with tar content. These results indicate that cigarette manufacturing and ﬁlter characteristics inﬂuence the PAH composition of mainstream smoke, but have no effect on the PAH content in sidestream smoke, which is the main determinant of smokers' and non-smokers' exposure to PAHs in environmental tobacco smoke. Copyright © 2004 John Wiley & Sons, Ltd.