The first complete sequences of functionally rearranged VK genes (abbreviations ref. 1) of subgroups II and III are reported. The genes have been cloned from lymphoid cell lines synthesizing KII or KIII light chains as evidenced from immunochemical analyses with anti-VK subgroup-specific antisera. These data, together with the sequence of a KIV gene (described in the accompanying paper) and those of previously published KI genes make possible a comparison of genes representative of the four known V region subgroups of human K light chains. The VKII gene is distinguished from the VKI, VKIII, and VKIV genes by a much longer intron within the leader sequence: 426 bp vs ca. 120-220 bp. Blot hybridization experiments with human DNA digests using probes from the KII and KIII genes and from the respective upstream regions help to define subgroup specific probes and hybridization conditions.