OBJECTIVE: The use of epidural steroid injections has increased dramatically, but knowledge of potential adverse effects is lacking. An association between steroid injection and subsequent abnormal vaginal bleeding has been suspected clinically, but evidence has been limited to anecdotal reports. STUDY DESIGN: Paired observational retrospective cohort study using electronic medical records from a large integrated health care system. Participants were all nonhysterectomized women who underwent epidural steroid injections in 2011. For each steroid injection, encounters for abnormal vaginal bleeding during the 60 days preceding and 60 days after the injection were compared as paired observations. For women found to have bleeding, medical records review was performed to examine menopausal status and bleeding evaluation outcomes. RESULTS: Among 8166 epidural steroid injection procedures performed on 6926 nonhysterectomized women, 201 (2.5%) procedures were followed by at least 1 outpatient visit for abnormal vaginal bleeding. Women were 2.8 times more likely to present with abnormal vaginal bleeding during the postinjection period compared with the preinjection period (P < .0001). Of the 197 women with postinjection bleeding, 137 (70%) were premenopausal and 60 (30%) were postmenopausal. Postinjection bleeding prompted endometrial biopsy evaluation in 103 (52%) cases, with benign findings for 100% of premenopausal women (59/59) and 95% of postmenopausal women (42/44). CONCLUSION: Epidural steroid injections are associated with subsequent abnormal vaginal bleeding for both premenopausal and postmenopausal women. Women undergoing epidural steroid injection should be advised of abnormal bleeding as a potential adverse effect and providers should be aware of this association when evaluating abnormal bleeding.