Objective: To report the first case of ciguatera-associated rheumatoid arthritis in Japan.

Patient: A 53-year-old man presented to our clinic with morning stiffness and pain in the fingers and wrists.

Results: For six months, he had suffered from chronic pain in both hands and shoulders caused by ciguatera poisoning. He was referred to a local general hospital and diagnosed with RA.

Conclusion: When synovitis becomes evident in chronic ciguatera poisoning, reevaluation is necessary, including investigation of chronic arthritis, which might be associated with the onset of RA.