SummaryTwo patients with Wiskott‐Aldrich syndrome were studied immunologically and biochemically. The same immunological abnormalities were found in these patients as described in the previous cases. Futher, the expression of IgG‐Fc receptor on the surface of monocytes was poor and anti‐D coated human erythrocytes were less phagocytized by these cells from the patients than by control cells. The hexokinase activity was low in mononuclear cells (30% of the control mean) but normal in erythrocytes. It was suggested that a disturbance of the energy metabolism may affect the antigen processing mechanism and the afferent limb of immunity in the immunocompetent cells in this di