Polycyclic aromatic hydrocarbons (PAHs) are a class of environmental pollutants created primarily from incomplete combustion of various organic materials including tobacco. Cigarette smoke is a complex mixture of various classes of compounds, including numerous PAHs, in both the mainstream and the sidestream smoke fractions. We measured the levels of 14 PAHs in mainstream smoke from unfiltered custom cigarettes made from individual tobacco types and 30 brands of domestic blended cigarettes using standardized smoking conditions, extraction from the Cambridge filter pads, and gas chromatography/mass spectrometry. Differences in smoke PAHs from cigarettes with selected tobacco blends were identified and illustrate how blend composition contributes to the overall mainstream smoke PAH profile. The PAH levels varied among the different commercial cigarette brands, with the amount of total mainstream smoke PAHs ranging from 1 to 1.6 microg per cigarette. Under machine smoking conditions, the mainstream smoke from domestic cigarettes had individual PAHs ranging from benzo[k]fluoranthene at levels below 10 ng/cigarette to naphthalene at levels of around 500 ng/cigarette. Low delivery cigarettes smoked with blocked filter vent holes dramatically increased the mainstream smoke PAH deliveries with respect to their unblocked counterparts. Inhalation of PAHs and other harmful chemicals from cigarette smoke are unique as they represent a routine voluntary exposure to common environmental pollutants.