This paper attempts to investigate the applicability of harmony search algorithm (HSA) to solve extremely challenging non-convex economic load dispatch problem with valve point loading effect, prohibited operating zones, ramp-rate limits, spinning reserve constrains and transmission losses involving variations of consumer load patterns. The performance of the proposed approach HSA has been tested successfully on the standard 6-bus, IEEE-14 bus and IEEE-30 bus system with several heuristic load patterns. The results of this study reveals that the proposed approach is able to find appreciable economical load dispatch solutions than those of improved fast evolutionary program and particle swarm optimization. Besides this, the transmission line losses are also considerably reduced and the computation time is reasonably even and less when compared to other methods. © 2012 Springer-Verlag.