Our purpose was to assess the long-term effect of treatment for thyroid dysfunction on musculoskeletal symptoms. Forty-six patients (37 with hypothyroidism, 9 with hyperthyroidism), who visited the outpatient clinic of rheumatology and had abnormal thyroid function tests on their first visit, cooperated in the study. They were interviewed with a structured questionnaire about their past and current musculoskeletal complaints. Thyroid dysfunction was considered the only explanation for the original musculoskeletal symptoms in 24 patients (Group I); in 19 patients an additional (rheumatological) diagnosis was made (Group II), and in 3 patients no apparent relation between musculoskeletal complaints and thyroid dysfunction was found. After treatment for thyroid dysfunction, the original complaints decreased in 52% and 47% of the patients in Group I and II, respectively. At the time of the follow-up study (mean follow-up duration 67 months) 91% of the patients had musculoskeletal symptoms, 80% of the patients said their present complaints were similar to their original symptoms. Treatment for thyroid dysfunction resulted in a temporary effect on musculoskeletal symptoms.