To evaluate the potential carcinogenic effects of formaldehyde, the proportionate mortality experience of embalmers licensed to practice in California [USA] was examined. Mortality was significantly elevated for total cancer, arteriosclerotic heart disease and suicide, whereas significant deficits were noted in mortality from diseases of the respiratory and genitourinary systems. Deaths from cancers of the brain, colon and prostate and leukemia were significantly higher than expected. No increased mortality was seen for cancers of the respiratory tract, including the nasal passages, where an effect might be expected based on animal studies. A parallel mortality survey of embalmers from New York State [USA] showed similar findings, with excesses of brain tumors, leukemia, colon cancer, arteriosclerotic heart disease and cirrhosis. Further investigation is needed to determine whether any of these outcomes is related to formaldehyde exposure.