This study examined the effect of increasing material-specific verbal and visual memory impairment severity on Rey 15-Item Test (RFIT) and RFIT/Recognition Trial performance. Data from 146 clinically referred patients (109 valid/37 invalid) who completed the RFIT, Brief Visuospatial Memory Test-Revised, and Rey Auditory Verbal Learning Test were analyzed. Rey Auditory Verbal Learning Test/BVMT memory impairment was operationalized as ≥40T (no memory impairment), 30T-39T (mild memory impairment), or ≤29T (severe memory impairment). Medium-to-large correlations emerged between the RFIT and memory measures. Significantly more patients with impaired visual memory, and to a lesser extent verbal memory, failed the RFIT and RFIT/Recognition. RFIT and RFIT/Recognition produced areas under the curve = .80-.90 for detecting invalidity and strong associated psychometric properties among patients without memory impairment, but both yielded low and largely unacceptable accuracy (areas under the curve = .57-.71) when verbal or visual memory impairment of any severity was present. In sum, RFIT performance was significantly affected by increasing material-specific memory deficits, such that it produced acceptable accuracy among unimpaired patients, but accuracy greatly diminished with memory impairment, which is antithetical to a sound performance validity test. (PsycInfo Database Record (c) 2020 APA, all rights reserved).