The aim of this paper is to estimate the uniaxial compressive strength (UCS) of rocks with different characteristics by using genetic expression programming (GEP). For this purpose, five different types of rocks including basalt and ignimbrite (black, yellow, gray, brown) were prepared. Values of unit weight, water absorption by weight, effective porosity and UCS of rocks were determined experimentally. By using these experimental data, five different GEP models were developed for estimating the values of UCS for different rock types. Good agreement between experimental data and predicted results is obtained.