The aim of the article is to present the selected results of analytical investigations concerning possible directions of reducing the unit production costs in the mining company together with some results of practical calculations. The investigations emphasize the role of the rate of utilising the production capacity leading to reducing the unit production costs. The main component having an essential influence on the unit production costs are the fixed unit costs. Two basic indices of a crucial meaning for searching for possibilities leading to decreasing the unit production costs are assumed. The first index (w1) is a measure of the rate of utilising the production capacity, the second one (w2) concerns the fixed costs coincided with the unit of the production capacity. Theoretical considerations concerning the mathematical modelling of the unit production costs as the values depending on the rate of utilising the production capacity and the fixed costs coincided with the production capacity unit, are presented in the first part of the paper. The rationalisation criteria of the mine unit production costs are formulated. These criteria can constitute the elements of restructuring program for the mining company. The calculation example with the use of the practical input data shows the impact of the rate of utilising the production capacity on the mine unit production costs. In the example two variants of annual working time are taken into account. Results of appropriate calculations are presented and analysed in an aspect of reducing unit costs of production as a result of increasing rate of utilising the mine production capacity.