Given a specified design the efficiency of a gamma irradiation facility can be improved by optimum adjustment of certain parameters (e.g. source positions, activity distribution, distance between the sources and the irradiation goods, dimensions of the irradiation container, etc.). The optimization problem is given by an objective function (efficiency, or throughput), which is to be maximized, and by constraints limiting the admissible range of the dose applied to the product. The general mathematical formulation of the problem is specified for different types of irradiation facilities (one or several conveyors, one or several containers in a stationary or an intermittent regime).