All sea turtle species are listed on the Red List of the International Union for the Conservation of Nature due to multiple threats. Among these, disease is a frequent cause of stranded sea turtles encountered in rehabilitation centers. Since 2013, we found joint swelling in 13 sea turtles belonging to all four sea turtle species submitted to the Kélonia Sea Turtle Observatory of Reunion Island, France. Affected sea turtles presented with lameness, anorexia, and lethargy. Polyarthritis was radiographically confirmed and lesions were characterized by progressive osteolysis of bones surrounding joints. Anterior flippers were affected in all cases and posterior flippers were also involved in some cases. We isolated several bacterial agents from blood and synovial fluid. We attempted a collective treatment with injectable florfenicol, based on sensitivity results, which was continued for 4 wk and then as needed based on radiographic evolution of the lesions. Radiographic stabilization of the lesions occurred in nine of 13 cases. We reviewed environmental conditions and optimized them to minimize stress that could predispose these rehabilitated sea turtles to opportunistic infections. Handling techniques used to move sea turtles were also improved. While we can make no conclusion regarding the cause of polyarthritis in this population of sea turtles, we successfully managed this poorly described problem in a rehabilitation setting.