We have designed a novel strategy for the isolation of the rearranged genomic fragments encoding the L-VH-D-JH and L-V kappa/lambda-J kappa/lambda regions of mouse immunoglobulin genes. This strategy is based on the PCR amplification of genomic DNA from mouse hybridomas using multiple specific primers chosen in the 5'-untranslated region and in the intron downstream of the rearranged JH/J kappa/lambda sequences. Variable regions with intact coding sequences, including full-length leader peptides (L) can be obtained without previous DNA sequencing. Our strategy is based on a genomic template that produces fragments that do not need to be adapted for recombinant antibody expression, thus facilitating the generation of chimeric and isotype-switched immunoglobulins.