In this paper a genetic algorithm for the flexible job-shop scheduling problem is presented. Given are a set of machines and a set of jobs consisting of operations which have to be sequenced in a fixed order. Each operation can be processed by a subset of the machines and its processing time depends on the assigned machine. The objective is to assign each operation to an appropriate machine and to sequence all operations on the machines such that the makespan is minimized. The authors propose a genetic algorithm in which solutions are represented by lists where for each operation the assigned machine is coded and the order of the operations in the list determines the sequences on the machines. Offsprings are generated by crossover operators either changing the machine assignment or the sequences. Computational results are reported for benchmark instances known from the literature.