A genetic algorithm is used to solve an economic dispatch problem. The chromosome contains only the encoding of a normalized incremental cost system. Therefore, the total number of bits of a chromosome is entirely independent of the number of units. In the first case, the transmission line losses are calculated using the Newton-Raphson method and kept constant. In the second case, the transmission line losses are considered as a linear function of the real generated power. The coefficients are calculated using the Gauss-Seidel method. This method has been applied to the western part of the Algerian power network, and the results have been found to be satisfactory compared with other results obtained using classical methods.