The recent increase in cigar consumption began in 1993 and was dismissed by many in public health as a passing fad that would quickly dissipate. Recently released data from the U.S. Department of Agriculture (USDA) suggests that the upward trend in cigar use might not be as temporary as some had predicted. The USDA now projects a total of slightly more than 5 billion cigars were consumed last year (1997) in the United States. Sales of large cigars, which comprise about two-thirds of the total U.S. cigar market, increased 18 percent between 1996 and 1997. Consumption of premium cigars (mostly imported and hand-made) increased even more, an astounding 90 percent last year and an estimated 250 percent since 1993. In contrast, during this same time period, cigarette consumption declined 2 percent. This dramatic change in tobacco use raises a number of public health questions: Who is using cigars? What are the health risks? Are premium cigars less hazardous than regular cigars? What are the risks if you don't inhale the smoke? What are the health implications of being around a cigar smoker? In order to address these questions, the National Cancer Institute (NCI) undertook a complete review of what is known about cigar smoking and is making this information available to the American public. This monograph, number 9 in a series initiated by NCI in 1991, is the work of over 50 scientists both within and outside the Federal Government. Thirty experts participated in the multi-stage peer review process. The conclusions presented in the monograph represent the best scientific judgment, not only of the NCI, but also of the larger scientific community.