Women with disabilities may be at higher risk of late-stage breast cancer. Using the 1991-93 Medicare-Surveillance Epidemiology and End Results (SEER)-linked data set, the authors compared stage at diagnosis and mortality, for Social Security Disability Insurance (SSDI)-qualifying women and similarly aged non-SSDI qualifying women. Disabled patients were diagnosed at a later American Joint Committee on Cancer stage. Disabled patients had higher all-cause mortality rates but had similar breast cancer-specific mortality. Disabled women belonging to Medicare HMOs tended to have earlier stage diagnosis and better survival compared to Medicare fee-for-service (FFS) insurance. In conclusion, disabled patients tended to be diagnosed with breast cancer at a later stage and to have higher mortality. These findings were more pronounced in Medicare FFS than in Medicare HMOs.