This paper presents a discussion of "A new honey bee mating optimization algorithm for non-smooth economic dispatch" Taher Niknam et al. Energy 34 (2009) 757-766. The discussed paper presented economic dispatch problem by experimenting three standard test systems considering 10, 15, and 40-units. However, in the reported results of test system 1, the total fuel cost calculations are different for the given generation schedule. In this discussion, clarification regarding cost calculation is presented. (C) 2012 Elsevier Ltd. All rights reserved.