STUDY OBJECTIVES: Insomnia is common among older adults and associated with an increased risk for falls. Determining if falls are more strongly associated with insomnia or prescribed hypnotic medications could be used to guide interventions to reduce falls risk. METHODS: We examined the prospective association of a diagnosis of insomnia and/or prescribed hypnotic medication use with the risk for serious fall injuries among 9087 Reasons for Geographic and Racial Differences in Stroke (REGARDS) study participants aged 65 years or older with Medicare fee-for-service health insurance at baseline (2003-2007). A diagnosis of insomnia was based on ICD-9 codes in Medicare claims and prescribed hypnotic medication use was determined through a pill bottle review. Serious fall injuries were identified by Medicare claims between baseline and December 31, 2018. RESULTS: Over a median of 6.8 years, 1660 (18.3%) participants had a serious fall injury. The incidence rates for a serious fall injury per 1000 person-years were 24.8 (95%CI: 23.5, 26.1), 28.8 (95%CI: 18.6, 38.9), 32.6 (95%CI: 28.2, 37.0), and 46.6 (95%CI: 26.7, 66.5) for participants without insomnia or taking prescribed hypnotic medication (-insomnia/-hypnotics), with insomnia only (+insomnia/-hypnotics), taking prescribed hypnotic medication only (-insomnia/+hypnotics), and with insomnia and taking prescribed hypnotic medication (+insomnia/+hypnotics), respectively. Compared with the -insomnia/-hypnotic group, the multivariable-adjusted hazard ratios for a serious fall injury were 1.13 (95%CI: 0.79, 1.61), 1.29 (95%CI: 1.11, 1.50), and 1.60 (95%CI: 1.01, 2.56) for +insomnia/-hypnotics, -insomnia/+hypnotics, and +insomnia/+hypnotics, respectively. CONCLUSIONS: The risk for serious fall injuries was higher for those taking prescribed hypnotic medications but not with an insomnia diagnosis.