Seventeen patients with intractable lupus nephritis and nephrotic syndrome were treated with total lymphoid irradiation. Statistically significant improvement in mean renal disease and serologic activity parameters occurred within 3 months and persisted for at least 3 years. Although there was a marked reduction of T helper cell numbers and function after total lymphoid irradiation, recovery of these parameters was not associated with a return of disease activity. Risks of sterility, severe infections, and hematologic malignancy appeared to be lower than with alkylating agents.