We describe a girl who presented at age 5 with objective signs of arthritis and was initially diagnosed as having juvenile rheumatoid arthritis. Over the following years, she developed slowly progressive joint deformities indicative of Jaccoud's arthropathy. When she was 11 years old, symptoms typical of systemic lupus erythematosus appeared, accompanied by anti-DNA antibodies. This case illustrates that in children also, Jaccoud's arthropathy may be a precocious manifestation of systemic lupus erythematosus.