A mortality study of phosphate fertilizer production (SIC-2874) workers was conducted. The purpose of the study was to determine whether there was an excess risk of death from any cause, and particularly from lung cancer. The cohort consisted of 3,199 workers, 2,981 males, employed at the facility from 1953 to 1976. The vital status of the cohort was determined as of December 31, 1977. A total of 176 subjects were found to be deceased; 163 death certificates were obtained. Standardized mortality ratios (SMRs) were calculated. There was a deficit for all causes of death combined, SMR 84, which was primarily due to a large deficit for diseases of the circulatory system. None of the cause specific SMRs were significantly elevated. The SMR for lung cancer was 113. When analyzed according to race, duration of employment, or length of followup, the SMRs appeared to increase for black males with both duration of employment and length of followup, although there were only a few deaths in each of these categories. A total of only five black males died of lung cancer. Black male workers with more than 20 years of employment had a lung cancer SMR of 1,250. The length of followup categories of 10 to 20 years and 20 plus years had SMRs of 173 and 357, respectively. The authors note that a statistically significant excess of lung cancer mortality was observed among black males in the longest duration of employment and followup categories. Although the small number of lung cancer deaths precludes any conclusion being drawn, this finding suggests a possible association with occupational exposure.