Blood samples from a group of 130 dentists and a control group of 40 blood-donors were analyzed by cold vapor atomic absorption spectrophotometry in order to evaluate the extent of mercury exposure. The median blood concentration of mercury was 4.0 (range: 1.2-19.2) micrograms/l for dentists and 2.0 (1.1-4.6) micrograms/l for controls (2P less than 0.01). Practice characteristics obtained in a questionnaire showed no statistically significant relationship to blood mercury, but 49 dentists having one or more fish meals per wk, had a median concentration of mercury, which was 47% higher than dentists seldomly consuming fish (2P less than 0.01). It was concluded that none of the examined dentists had blood concentrations above the level (35 micrograms Hg/l) associated with the hygienic threshold limit.