Abstract: The Salisbury screen is the basic design of absorbers, it has a good absorbing properties at the resonantfrequency. However, the thickness of the absorber must be? / 4 , that is not suitable for engineering applications. In this paper, wedemonstrate that placing a resistive sheet in close proximity to a lossy frequency selective surface, and reducing the overallthickness of the absorber, we can design a electromagnetic band gap absorber. Meanwhile, the geometrical structure andcorresponding resistance of the lossy frequency selective surface, the thickness and unit cell size of the absorber is optimized byusing a genetic algorithm to achieve the thinnest possible absorber. Two examples of genetically engineered electromagnetic band gap absorbers are presented and discussed.