Purpose <p>To retrospectively evaluate the outcomes of displaced ankle fractures treated with plaster versus fiberglass splints at a single academic institution.</p> Methods <p>A retrospective review was conducted at an Academic Level 1 Trauma center of a consecutive series of patients age 18–99 with displaced ankle fractures requiring closed reduction and splinting in the emergency department from January 1, 2017 to April 1, 2022. There was a change in institutional preference from fiberglass to plaster splints at the half-way point of this study period. The primary outcome measure was maintenance of fracture reduction. Secondary measures included treatment cost, reduction quality, and splint-related complications.</p> Results <p>Three hundred and sixty-five patients were included in the study, with three hundred and seventy-two ankle fractures. This cohort involves a consecutive series of patients treated before and after switching from fiberglass to plaster splints. Mean age was 49 ± 19.1&#xa0;years. One hundred and thirty-six males and two hundred and twenty-nine females were enrolled. No significant difference was found between sex, BMI, laterality, or fracture type between fiberglass or plaster splint treatments. Further, no significant difference was found regarding the rate of lost reduction, the incidence of multiple reduction attempts, and the incidence of skin complications between the two splint treatments. Fiberglass splints were found to be close to three times the cost of plaster splints ($21.13 vs. $7.64).</p> Conclusions <p>The use of plaster splints is non-inferior and more cost-effective than fiberglass splints for the treatment of ankle fractures.</p>