BACKGROUND: The first probable case of human brucellosis in Korea was reported in 2002. Since then there has been a gradual increase in the incidence and prevalence of the disease. There has not been any long-term follow-up investigation of the clinical course and serologic profiles of the disease in Korea. The present investigation is a 3 year clinical and serologic follow-up of human brucellosis patients in Chonbuk province. MATERIALS AND METHODS: The investigation involved a total of 11 patients who were positively diagnosed with brucellosis in 2003. Clinical manifestations were evaluated either directly or via telephone interviews. The serologic follow-up was done by standard tube agglutination test (SAT). Negative sero- conversion was defined as an SAT titer less than 1:40. Early convalescence was defined as clinical manifestations of brucellosis observed within 12 months of diagnosis, and delayed convalescence was defined as clinical symptoms persisting longer than 12 months. RESULTS: A total of eleven patients (8 males and 3 females; with a mean age of 45 years) participated in the study. Ten patients were livestock workers and one was a practicing veterinarian. Three years after the initial diagnosis, chronic fatigue and arthralgia were persistently observed in more than 60% of the patients in delayed convalescence. There was no evidence of relapse or reinfection of the disease. The median duration of antibiotics treatment and serologic follow-up were 11 weeks and 22 months, respectively. Negative sero-conversion was noted between 5 and 16 months after the initiation of treatment (with a median 11 months). CONCLUSION: Although the human brucellosis patients developed chronic symptoms such as fatigue and arthralgia even after negative sero-conversion, there was no evidence of any relapse or reinfection. This may mean that antibiotic intervention is not a justifiable recommendation. We also suggest that serologic monitoring be performed for at least 16 months after the initiation of treatment.