Escherichia coli is a model organism for biochemical and biological studies as it is one of the best characterised prokaryote. Two-dimensional polyacrylamide gel electrophoresis, computer image analysis and different protein identification techniques gave rise, in 1995, to the Escherichia coli SWISS-2D PAGE database (http://www.expasy.ch/ch2d/). In the E. coli 3.5-10 SWISS-2D PAGE map, 40% of the E. coli proteome was displayed. The present study demonstrated that the use of narrow range pH gradients is able to potentially display up to a few copies of protein per E. coli cell. Moreover, the six new E. coli SWISS-2D PAGE maps (pH 4-5, 4.5-5.5, 5-6, 5.5-6.7, 6-9 and 6-11) presented here displayed altogether more than 70% of the entire E. coli proteome.