The course of disease in 187 patients with systemic juvenile chronic arthritis was documented in a retrospective study 2-20 years after onset. Despite differences in joint involvement in the first 6 months of the disease, most of the patients subsequently developed a polyarthritis leading to severely impaired function in approximately 50% of them. Advanced degenerative changes identified by roentgenography were found in particular in the wrist and hip joints. There was an overall regression in the frequency of the extra-articular symptoms and the humoral pathologic activity. Fifteen years after the onset of disease only 30% of the patients still had systemic signs, and humoral activity was found in less than 50%. The mortality rate of 14% was primarily due to infections and kidney failure in amyloidosis. The course varies considerably from child to child. It has not so far been possible to differentiate prognostic factors for different subgroups.