We report the 1946-1992 mortality experience of 4008 females employed in any of 10 U.S. fiberglass manufacturing plants between 1945 and 1978 relative to external population rates. We also examine respiratory system cancer (RSC) mortality as a function of estimated exposure to respirable fibers (RFib), formaldehyde (FOR), silica, phenolics, urea, and other agents based on internal cohort comparisons. No statistically significantly elevated standardized mortality ratios were observed for all-cause mortality (930 deaths), any of the 25 nonmalignant causes considered, all malignant neoplasms (266 deaths), or any of the 27 malignant causes considered. Internal cohort comparisons revealed no significant positive associations between RSC mortality (53 cases) and exposure to RFib, FOR, or any of the other agents considered, although exposure levels were generally low. Some demographic subgroups appear to be at relatively increased risk of RSC.