In a clinical study the tolerance and efficacy of a gamma-globulin, treated at pH 4, has been studied. This preparation manufactured by the "Zentrallaboratorium des Blutspendedienstes SRK" can be given intravenously without any risk of untoward reactions. It has been applied in high dosages up to 99 g per week. In 15 cases with primary humoral immunodeficiency, the frequency and the severity of acute bacterial infections were markedly reduced or completely absent. In 16 patients without antibody deficiency but suffering from severe septic-toxic infections, results with Immunglobulin SRK were encouraging and warrant further controlled studies.