The construction of efficient compilers is very complex, since it has to contend with various optimization problems and depends on the characteristics of the architecture of the machine for which they generate code. Many of these problems are NP-hard. The genetics algorithms have been shown to be effective in the resolution of difficult problems, however, their use in compilation is practically non-existent. In this paper we propose a solution to the problems of register allocation and instruction scheduling. We carry out an analysis of performance by comparing with the more traditional approaches for these problems and we obtain profits on the speed of the generated code varying between -2% and 26%.