The paper presents themethod of variable costs evaluation in costs of coal production. Themethod is based on construction of econometric models in which the dependence of analyzed costs item from coal production is seek. The rationale of the form of applied equation is given where the dependence of costs from two variables is investigated: production and time. The analysis was done for the mines of Jastrzebska Coal Company. The series of data investigated were the monthly data for 2008 year and for the 2007 and 2008 years. A number of econometric models have been validated and on their basis the shares of variable costs in costs of coal production and in costs of sold coal have been identified. The imperfections of the method is pointed out in the paper and the direction of further analyses is shown lying in interrelation of system of costing by products and system of costing by kinds of costs.