Synovial fluid eosinophilia in Lyme disease

We describe three 14-year-old boys who developed synovial fluid eosinophilia associated with Lyme disease. One patient, with arthritis that began in 1975, had the first documented case of Lyme disease in New Jersey. Lyme disease should be considered when eosinophilia is noted on analysis of synovial fluid from patients with undiagnosed arthritis.