Mortality patterns due to occupational exposures among 3,369 white male members of the United Association of Journeymen and Apprentices of the Plumbing and Pipefitting Industry were examined using death benefit claims in 1971 and death certificates. Workers were divided into six general trade categories: plumbers, pipefitters, sprinklerfitters, steamfitters, lead burners, and metal tradesmen. Compared to calculated expected age and cause specific death ratios, a significant excess was found in the study group for all malignant neoplasms, and cancers of the esophagus, respiratory system, lung, bronchus, trachea, and other sites. These excesses apparently were confined to workers in the building trades division and plumbers by trade. The authors conclude that excess mortality experienced by the plumbers from malignant neoplasms of the lung/bronchus, esophagus, and lymphatic/hematopoietic tissues, and other sites might be due to occupational exposures. Further study, using more detailed information on exposures, employment, smoking, and alcohol consumption, is recommended.