The isolation of the rearranged immunoglobulin genes from a hybridoma cell line, which is a prerequisite for the construction of a recombinant antibody, can easily be achieved by PCR. We have determined the nucleotide sequence of the variable region of L chain of a high affinity monoclonal antibody HAb27 directed to human hepatocarcinoma. Analysis of the nucleotide sequence of the light chain V region of HAb27 revealed that the V kappa sequence was 85% identical to germline V kappa Ox1 sequence.