To develop a phage display of single-chain antibodies (scFv), fractions of total cell DNA and RNA were obtained from splenocytes of naive mice. The DNA fragments encoding variable regions of light and heavy immunoglobulin chains were amplified and isolated using primers specific to the conservative regions of these genes. The construction of the library was based on the principle of stochastic combining the DNA fragments encoding the light and heavy antibody chains with the DNA linker, whose structure corresponded to the (Gly4Ser)3sequence. The scFv library was constructed using the E. coli TG1 strain and the phagemid vector pHEN1. The repertoire of the library exceeded 5 × 107independent recombinant clones. The clones producing antibodies to human granulocyte colony-stimulating factor were isolated. The affinity constants of the resulting scFv were in the range of 2 × 104to 1.8 × 107M-1.