Common variable immunodeficiency (CVID) is presumed to be a heterogenous group of disorders with potentially separate etiologies. Memory B cell subsets, characterized by CD27 expression, have been suggested as a means to subclassify CVID patients. 53 patients were subdivided based on percentages of switched memory B cells (CD27+IgM-IgD-): 33 were placed in Group I (<0.4% CD27+IgM-IgD- cells/peripheral lymphocytes) and 20 in Group II (>0.4%). The median serum IgG for subjects in Group I was lower at 145 mg/dl vs. 329.5 mg/dl for Group II (P=0.038). Post-pneumococcal vaccine IgG response was tested; the median protective response was 0.5 serotypes for Group I and 3 serotypes for Group II (P=0.041). Autoimmune and granulomatous disease was found in higher rates in Group I. CVID patients with decreased percentages of switched memory B cells have lower levels of serum IgG, less effective pneumococcal vaccine antibody responses, and higher rates of autoimmune and granulomatous disease.