During an investigation of a novel interstitial lung disease in a cohort of nylon flock workers, a former worker was found to have developed bilateral synchronous pulmonary adenocarcinomas three decades after he quit smoking, suggesting that exposures in this industry might pose excessive risk of lung cancer. We conducted a retrospective cohort study of lung cancer incidence in the original study cohort (n=162) from August 15, 1998, to August 14, 2008. The Rhode Island Cancer Registry identified cohort members with lung cancer and provided age-gender-era-specific rates of lung cancer in Rhode Island. Five cases of lung cancer occurred among cohort members versus 1.61 cases expected for a standardized incidence ratio of 3.1 (95% CI, 1.01-7.23). The observed threefold increase in lung cancer incidence could not be readily ascribed to chance, study bias, or uncontrolled confounding. Workers in this industry should be notified of their potentially increased risk of lung cancer.