In the time period 1990-2004 we conducted a multisite case-control study in order to examine the relationship of mate consumption and risk of 13 cancer sites in Montevideo, Uruguay. The study included 13,201 participants (8,875 cases and 4,326 controls) drawn from the four major public hospitals in the city of Montevideo. Newly diagnosed and microscopically confirmed cases of cancers of the mouth, pharynx, esophagus, stomach, colon, rectum, larynx, lung, female breast, cervix uteri, prostate, bladder and kidney were included in the study. Controls were drawn from the same hospitals and in the same time period and were afflicted by non-neoplastic conditions not related with tobacco smoking or alcohol drinking and without recent changes in their diets. Odds ratios for mate consumption was directly associated with cancers of the upper aerodigestive tract (UADT), esophagus, stomach, larynx, lung, cervix uteri, prostate, bladder, and kidney. In conclusion these results suggest that chemicals, like benzo[a]pyrene, could be responsible of the carcinogenic effect of mate in the above mentioned cancer sites.