In 1982, approval of FDA for Eli Lilly's recombinant human insulin was just the prelude to the use of Escherichia coli as a host strain for recombinant protein production. After two decades, although many alternative organisms such as mammalian and plant cells are now being used for recombinant protein production, E. coli still remains the most valuable host for the production of recombinant proteins because of the advantages such as fast growth, well--characterized genetics, availability of numerous vector systems and high cell density culture (HCDC) technologies. In recombinant E. coli, once an optimal expression system is constructed, protein production can be enhanced by cellular engineering. Especially, during the HCDC, suitable cellular engineering strategies are required for the increase of the specific productivity of proteins. Here, we review the recent progress in the cellular engineering useful for the enhanced production of recombinant proteins in HCDC of E. coli.