Plasma exchange with either fresh-frozen plasma or 5% albumin solution as replacement fluid was performed in four selected patients with juvenile rheumatoid arthritis unresponsive to standard therapy. One 13-year-old boy with life-threatening systemic disease experienced a partial remission of disease and tolerated a decrease in prednisone dose from 15 to 4 mg daily following 14 exchanges with FFP. A 14-year-old girl, dwarfed by systemic disease and long-term corticosteroid therapy, was able to discontinue prednisone and grew 6.3 cm in 11 months following 18 plasma exchanges with FFP. An 8-year-old girl with pauciarticular disease, antinuclear antibody, and uncontrollable iridocyclitis underwent 16 plasma exchanges with 5% albumin solution as replacement; despite removal of antinuclear antibody, her eye disease and arthritis were not helped. A 16-year-old girl with erosive, polyarticular JRA showed no detectable change in her articular disease following nine exchanges. Transient decreases in hematocrit, complement components, and immunoglobulin concentrations occurred. In three patients Westergren sedimentation rate decreased for up to five months after exchanges. One patient died suddenly during an exchange with FFP; the cause of death appeared related to microemboli of unknown nature found in the lungs at autopsy. Plasma exchange should be done only in an intensive care setting and as a research procedure for children with JRA.