OBJECTIVE: Mixed connective tissue disease(MCTD) was first described by Sharp and coworkers in 1972 as distinct rheumatic diseases characterized by the overlapping features of systemic lupus erythematosus (SLE), systemic sclcrosis (SSc) and dermatomyositis/polymyositis and associated with the serologic marker anti-nRNP antibody at high titer. METHODS: We reviewed 18 cases(all females) of MCTD who were admitted or visited to rheumatism center of Hanyang University Hopital, from October 1989 to September 1992. RESULTS: 1) The average age at onset of MCTD was 38.6 years. The average duration of the disease was 5.3 years. 2) Raynaud's phenomenon was found in 100%. Arthritis was found in 13 cases but rheumatoid factor was found in 15 cases. 3) Hand swelling was found in 15 cases and myositis was found in 56% (10 cases). 4) All patients with MCTD have anti-nRNP antibodies by high titer. In general, the titer does not correlate with disease activity. CONCLUSIONS: These data suggested that the clinical features of MCTD in Korean patients revealed similar to those of previous reports regarding foreign ethnic groups.