The cause specific mortality patterns among approximately 59,000 steelworkers in Allegheny County, Pennsylvania between 1953 and 1975, were compared to those among coke oven workers at 10 factories outside of Allegheny County between 1951 and 1975. Within the steel industry, the mason department, the foundry, and several secondary mills were identified as needing mortality studies. Among Allegheny County coke oven workers with 5 or more years at the ovens, there was an excess of lung cancer deaths, especially for black workers. There also was an excess of kidney cancer deaths, especially among white workers, and an overall increase in deaths from nonmalignant respiratory diseases. Among coke oven workers outside of Allegheny County, the lung cancer death rate among whites and blacks was comparable. These workers had a slight increase in deaths from kidney cancer, and cancer of the prostate and buccal cavity. Between 1968 and 1975, Allegheny County steelworkers had rates similar to those of the general population for all causes of death. The authors conclude that the length of follow up must be considered when studying the mortality of an industrial cohort. They note that it is difficult to draw inferences from a comparison of the mortality patterns of the general population and an industrial cohort. The authors recommend continued record maintenance and use of this steelworkers cohort for future studies.