A proportionate mortality study of a cohort of golf course superintendents was conducted using death certificates for 686 deceased members of the Golf Course Superintendents Association of America who died from 1970 to 1992. White males were included in the study population from all 50 states. The study objective was to compare mortality from this cohort to the general U.S. white male population. The proportionate mortality ratio (PMR) for all types of cancer was 136 (CI: 121, 152). Significant excess mortality from smoking-related diseases was observed. The PMR for arteriosclerotic heart disease was 140, which was significantly elevated (CI: 127, 155). In addition, the PMR for all respiratory diseases was 176 (CI: 135,230), while the PMR for emphysema was 186 (CI: 101,342). The PMR for lung cancer was 117 (CI: 93, 148). Mortality for four cancer types--brain, lymphoma (non-Hodgkin's lymphoma, NHL), prostate, and large intestine--occurred at elevated levels within this cohort: brain cancer PMR = 234 (CI: 121,454), non-Hodgkin's lymphoma (NHL) PMR = 237 (CI: 137,410), prostate cancer PMR = 293 (CI: 187,460), and large intestine cancer PMR = 175 (CI: 125,245). The PMR for diseases of the nervous system was 202 (CI: 123,333). A similar pattern of elevated NHL, brain, and prostate cancer mortality along with excess deaths from diseases of the nervous system has been noted among other occupational cohorts exposed to pesticides.