The nonmalignant effects of chronic chlorinated naphthalene exposure were examined in workers who had been employed at a cable factory during World War II. Cases of chloracne and liver disease were identified using employee medical records. Death certificates were obtained and mortality rates, relative to the United States and Westchester county, were determined. Of the 9,028 workers studied, 460 had been diagnosed with chloracne. Of these 460 workers, 59.6% were deceased, whereas 50.3% of the total cohort were deceased. Acute yellow atrophy of the liver caused eight deaths among the workers; all were male and three had chloracne. Ten additional employees were diagnosed with liver dysfunction. The standardized mortality ratio (SMR) for cirrhosis of the liver in the total cohort, 1.84, was significantly higher than that of the chloracne subcohort, 1.51. The SMR for cirrhosis among white males, 2.06, was significantly higher than that among white females, 1.22. A small but statistically significant increase in ischemic heart disease was also observed in this cohort, with an SMR of 1.07. The authors conclude that the excessive number of deaths caused by cirrhosis of the liver is attributable to the chronic effects of chlorinated naphthalene exposure.