Purpose: To investigate differences in the performance of polyether ether ketone (PEEK) frameworks vs traditional metal frameworks for removable partial dentures (RPDs) in terms of OHRQoL, patient preference, periodontal indices, and denture satistfaction. Materials and Methods: Twenty-six participants were recruited to a randomized controlled crossover trial and were provided with either PEEK or cobalt-chromium (Co-Cr) RPDs. After 4 weeks, the participants were provided with the other RPD. After both 4-week testing periods, the participants chose their preferred RPD and were followed up again at 6 months and 1 year. The primary outcome measure was effect on OHIP-20 score, which was compared among patients using repeated measures ANOVA. Secondary outcomes were participant preference compared using chi-square analysis; Plaque Index and Gingival Bleeding Index (PI and GBI, respectively) compared using repeated measures ANOVA; and McGill Denture Satisfaction Questionnaire (MDSQ) score compared between the two 4-week follow-ups using paired-samples t test. Results: Both Co-Cr and PEEK frameworks resulted in a significant improvement in OHIP-20 score (P .001), but the material was not a significant factor in changes over 1 year (P = .87). There were no statistically significant differences in participant preference at 1 year (P = .491), nor between RPD materials in their effect on GBI (P = .476), PI (P = .967), or MDSQ (P = .368). Conclusion: Both Co-Cr and PEEK RPDs improved OHRQoL to a degree greater than the minimum clinically important difference at 4 weeks, 6 months, and 1 year compared to baseline. No significant preference or improved denture satisfaction score was seen for either material. PEEK frameworks seem to be associated with similar degrees of periodontal effects as Co-Cr frameworks.