An epidemiological study was conducted to determine the mortality of dentists in comparison with that of the general population and of physicians. A cohort of 11,478 white male dentists practicing in New England from 1921 to 1960 has been identified from the records of the State licensing authorities. Leukemia mortality has approximated that expected from several sets of standard rates, both in the entire cohort and in that group entering dental practice prior to 1921. Mortality from all causes has been less than that expected from death rates of the New England white male population and U.S. physician population, but greater than that of certain medical specialists. Cancer mortality has been significantly less than, and mortality from cardiovascular diseases about equal to, that of the general population. Suicide is the only cause of death with greater than expected mortality throughout the study period. No relationship between mortality and exposure to ionizing radiation was observed. (Author)