A prospective study was conducted of 2,646 employees who worked 3 mo. or more during Jan. 1957 through July 1983, in a manufacturing plant that used tricholorethylene as a degreasing agent. Of the study cohort 98% were traced; they accounted for 16,338 person-yr of employment and 38,052 person-yr of follow-up. Mortality experience was generally more favorable than that of the comparable segment of the USA population over the same period of time. For the white male cohort there were fewer deaths than expected from heart disease, cancer and trauma (standard mortality rate for all causes = 0.79, P < 0.01). Reports by requiring medical treatment showed that there were only 1/3 as many persons with heart disease or hypertension as were reported in a comparable reference population studied over the past 5 yr.