Objective: To evaluate mortality from cancer and other diseases among 4863 women employed at eight North American styrene-butadiene rubber plants. Cancers of the lymphohematopoietic tissues, breast, and ovary were of strongest a priori interest. Methods: Cause-specific standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) were estimated. Results: The observed number of deaths was approximately equal to that expected for leukemia (10 observed/13 expected), Hodgkin lymphoma (1/1.6), multiple myeloma (7/7.9), non-Hodgkin lymphoma (15/14), and cancers of the breast (72/74) and ovary (21/22). Ever-hourly women had more than expected deaths from lung (47/30, SMR = 159, CI = 117 to 211) and bladder (6/1.8, SMR = 332, CI = 122 to 723) cancers. Exposure-response analysis, done only for lung cancer, indicated no trend for butadiene or styrene. Conclusions: The observed excesses of lung and bladder cancers may be attributable to nonoccupational factors rather than to workplace exposures. © 2009 by American College of Occupational and Environmental Medicine.