This is an update of a previous review of epidemiological evidence pertaining to the human carcinogenic potential of triazine herbicides. In 36 studies evaluated, atrazine was the most common triazine investigated. In general the studies were limited by lack of in-depth exposure measurements and by small numbers of subjects with potential high exposure and/or with many years of follow-up since first exposure. Non-Hodgkin lymphoma, prostate cancer, and breast cancer were most frequently investigated. Only one to three analytical or ecological studies investigated Hodgkin lymphoma, leukemia, multiple myeloma, soft tissue sarcoma, hairy-cell leukemia, melanoma, and cancers of the ovary, testes, colon, stomach, lung, brain, bladder, buccal cavity, and pharynx. Results of these studies were typically imprecise and did not form an adequate basis for determining if triazine exposure causes any form of cancer. Collectively, the available epidemiology studies do not provide consistent, scientifically convincing evidence of a causal relationship between exposure to atrazine or triazine herbicides and cancer in humans. Based upon the assessment studies, there is no scientific basis for inferring the existence of a causal relationship between triazine exposure and the occurrence of cancer in humans.