Two girls with mixed connective tissue disease (MCTD) were treated in our hospital in the past 5 years. Patient 1, a 10-year-old girl presenting with migratory arthralgia, had an initial diagnosis of juvenile rheumatoid arthritis. Muscle weakness with elevated levels of creatine kinase and liver enzymes, sclerodactyly, Raynaud's phenomenon and heliotrope sign developed subsequently in the following 3 years. Patient 2, a 13-year-old girl, had been treated for suspected systemic lupus erythematosus since 9 years of age. She presented with lymphadenopathy, arthralgia, pericardial effusion, and paralytic ileus. The symptoms waxed and waned. Sclerodactyly, Raynaud's phenomenon, proteinuria, and hypertension were also noted. Both patients had high serum titers of antinuclear antibody (speckled pattern, 1:5120) and were seropositive for antiribonuclear protein antibody. Intravenous immunoglobulin, prednisolone, cyclosporine A, and nonsteroidal anti-inflammatory drugs (NSAIDs) were given to patient 1. Patient 2 received cyclosporine A, prednisolone, and methylprednisolone pulse therapy. The disease has been well controlled for 2 years by low-dose immunosuppressants and NSAIDs. MCTD is a rare juvenile rheumatic disease: early identification and appropriate treatment can improve the disease outcome.