This article analyses the relationships between the qualitative parameters of brown coal supplied to power plants. The analysis was carried out based on averaged daily data on the quality of deliveries between 2004 and 2006. The basic objective of the analysis has been to determine the relationships between the qualitative parameters (as received): calorific value (Q), sulphur content (S) and so-called ballast (total ash and moisture content - [A + W]). As the analysis showed that no reliable relationship between sulphur content and the other parameters was observed. Considering the effect of this parameter would involve the potential for large errors. The most important relationships were found between the calorific value and ballast. The relationships discovered, with reference to calorific value confirm the trends that should be expected and are related to the operating properties of brown coal. Regressive calculations were made for the Q = f(A + W) and (A + W) = f(Q) dependencies, which allowed for the qualitative evaluation of how a change in some parameters affects the others. Calculations were performed for coal from individual mines and for individual years and for the entire brown coal sector. As a result of the calculations, equations were elaborated which, with great accuracy, depict the relationships between selected qualitative parameters.