Pipe or cigar smoking traditionally has been considered a less risky alternative to cigarette smoking. Some surveys and experimental studies have suggested, however, that former cigarette smokers who switch to cigars and/or pipe (CP) are more likely to inhale than CP users who never smoked cigarettes; but this relationship has not been consistently noted. To clarify smoke-exposure levels from CP smoking, smoking histories and serum thiocyanate (SCN) levels were studied in 9,106 adults aged 25 to 74 years in population-based surveys of seven upper Midwestern communities. Analyses of the 306 male CP smokers indicated a significantly higher SCN level in the ex-cigarette-smoking CP users vs the CP users who never smoked cigarettes. Serum thiocyanate levels of both CP groups were significantly higher than those of non-smokers and lower than cigarette-only smokers. However, the number of pipe bowls or cigars smoked per day was also significantly related to SCN levels, and this could account for much of the association between SCN and previous cigarette smoking status. Individuals currently smoking four or more pipe bowls or four or more cigars per day had an elevated smoke exposure equivalent to about ten cigarettes per day, whether or not they previously smoked cigarettes. Because of these findings and because former cigarette smokers were more likely to report heavy CP usage, cigarette smokers should be advised to quit rather than to switch to a pipe or cigar.