A method of obtaining at least one recombinant antibody with improved affinity for a selected antigen from a family of antibodies which bind the selected antigen comprising: a) obtaining a family of two or more antibodies which bind the same antigen in which the VH CDR3 amino acid sequence of each antibody in the family is the same length and greater than 60% identical at the amino acid level; b) re-pairing the VH region of an antibody obtained in step (a) with the VL region from a different antibody obtained in step (a) to produce a new recombinant antibody; and c) screening the recombinant antibody produced in step (b) and selecting said antibody if it has improved affinity for the selected antigen compared to any one of the antibodies obtained in step (a).