Antibody libraries came into existence 15 years ago when the accumulating sequence data of immunoglobulin genes and the advent of the PCR technology made it possible to clone antibody gene repertoires. Phage display (most common) and additional display and screening technologies were applied to pan out desired binding specificities from antibody libraries. "Synthetic" or "semi-synthetic" libraries are from naïve, non-immunized source and considered to be a source for many different targets, including self-antigens. We describe here how to construct a large human synthetic single-chain Fv (scFv) antibody library displayed on phages, where in vivo-formed complementarity-determining regions (CDRs) are shuffled combinatorially onto germline-derived human variable-region frameworks.