Persistent glomerulonephritis with low serum hemolytic complement activity and serum β1C globulin level has been reported in children and young adults. The disease, characterized by intermittent episodes of gross hematuria and nephrotic syndrome, often progresses to severe renal failure. Depressed serum β1C globulin and deposits of β1C on the basement membrane indicate a possible immune etiology and favorable response to immunosuppressant drugs might be expected. Seven patients with persistent hypocomplementemic glomerulonephritis were treated with azathioprine and prednisone for periods up to 4½ years. Two patients are asymptomatic and have normal renal function; another has normal creatinine clearance. The other four patients progressed to renal failure; two of these have died despite vigorous therapy. Limited response to immunosuppressants and lack of correlation of β1C globulin levels with clinical status suggests a possible nonimmune origin of this disease.