Concanavalin A-activated suppressor cell function was evaluated in patients with biopsy-proved primary glomerular disease. All three patients with minimal-change nephrotic syndrome had significantly greater suppressor activity than controls (percentage suppression 70 ± 4% mean ± SEM vs 29 ± 5%). Ten patients with glomerular immunoglobulin deposits and proteinuria had a normal mean suppression activity: but the individual suppressor activity varied widely. These results suggest that patients with certain types of primary glomerular disease may have altered suppressor cell function.