AbstractThe distribution of the major VLsubgroups (VλI, VλII, VλIII, VλIV, VλVI, and VλVIII) among λ‐type immunoglobulins (Igs) in normal serum was determined by a sandwich enzymelinked immunosorbent assay (ELISA) using a panel of murine anti‐human Vλ‐subgroup‐specific monoclonal antibodies (MoAbs) and appropriate reference standard proteins. The mean concentration of λI, λII, λIII, λIV, λVI, and λVIII Igs in serum specimens obtained from 23 adults was 2158, 162, 1958, 264, 225, and 169 μg/mL and represented 44, 3, 40, 5, 5, and 3% of the total Igλ population, respectively. The low percentage of λII Igs in normal serum was in marked contrast to the ∼40% incidence of this Vλsubgroup found among λ‐type Bence Jones proteins and monoclonal serum Igs obtained from patients with multiple myeloma and AL amyloidosis, or ∼60% in Waldenström's macroglobulinemia. The non‐random expresson of the VλII subgroup in these diseases implies a relationship between Vλ‐gene usage and plasma cell, as well as certain types of lymphoc