The risk associated with pancreatic cancer was examined in 46,384 employees of three automobile manufacturing facilities. Mortality data were obtained from death certificates. Among the 10,159 deceased workers, 97 cases of pancreatic cancer were observed. A total of 1,825 controls were selected from within the cohort. Exposure to metalworking fluids (MWFs) was assessed quantitatively. Although MWF exposures tended to be higher for cases than for controls, no significant differences between mean exposures were determined. The odds ratio (OR) for years of exposure to synthetic MWFs and grinding with synthetic MWFs was 1.07. For years of exposure to nitrosamine, biocide, and aluminum (7429905) components, the ORs equaled 1.08, 1.07, and 1.09, respectively. When cumulative exposures were lagged 0, 10, and 20 years, the OR for grinding with synthetic MWFs increased from 1.03 to 1.05 to 1.21, respectively. An OR of 1.64 was calculated when the duration of aluminum exposure was lagged 20 years. An OR of 2.8 was calculated for the high synthetic MWF exposure category, in which the mean exposure level was 5.5mg/m3. An OR of 3.0 was determined for the high grinding synthetic exposure category. Dose dependent increases in risk were noted for exposures to MWFs containing nitrosamines and aluminum. In the highest exposure categories, the ORs equaled 2.1 for nitrosamines, 2.2 for aluminum, and 4.5 for biocides. Exposures to synthetics, biocides, and nitrosamines occurred most in one factory and not at all in another. Among blacks, elevated ORs were calculated for grinding work. The authors conclude that exposure to synthetic MWF in grinding operations is associated with pancreatic cancer.