PURPOSE: Assessment of the middle ear muscle reflex (MEMR) is a standard part of the clinical audiological test battery that is used to assess middle ear function and identify possible retrocochlear lesions. The use of a wideband MEMR probe allows for additional information across frequency and lower reflex thresholds compared to the standard tonal probe used clinically. Recent animal studies suggest that the wideband MEMR is sensitive to noise-induced cochlear synaptopathy, the selective loss of the synaptic connections between the inner hair cells and the afferent auditory nerve fibers. However, the clinical utility of the wideband MEMR as an indicator of cochlear deafferentation is still unclear. Prior to adoption of the wideband MEMR as part of a diagnostic battery for cochlear deafferentation, it is necessary to determine the test-retest reliability of the measurement. METHOD: In a sample of 45 adults with normal hearing and normal tympanograms, wideband MEMR magnitude and threshold were measured at two different test sessions in response to a contralateral broadband noise stimulus at elicitor levels ranging from 60 to 100 dB SPL. The time between test sessions ranged from 2 hr to 5 months. RESULTS: Test-retest differences increased with elicitor level. In some individuals, there were changes in the magnitude and/or the frequency response of the MEMR between test sessions. CONCLUSION: When wideband MEMR testing becomes clinically available, test-retest differences in contralateral wideband MEMR magnitude and threshold can be referenced by clinicians to help with interpretation of wideband MEMR test results. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.28454612.