As part of a long-term inhalation bioassay study of cigarette smoke in rats, a detailed dosimetric comparison of three groups of rats exposed to smoke from different cigarette types was performed. Groups of 20 female F-344 rats were exposed, in Maddox-ORNL smoking machines, to 14C-dotriacontane-labeled smoke from three types of research cigarettes: high tar-low nicotine, low tar-high nicotine, and high tar-high nicotine. Analyses of lung tissues revealed similar deposition amounts and patterns of particulate matter for all three cigarette types even though the chamber smoke concentrations varied substantially. These results suggested that for rats exposed to different types of cigarette smoke, the amount of particulate material deposited may not be a function of concentration only. The authors conclude that when comparing cigarette smoke inhalation studies of different cigarette types, exposure parameters and smoke composition may both influence the amount of smoke inhaled and deposited in the lung and other organs.