Recently a few papers appeared on throughput scheduling, dealing with the relationship between batch structure and process structure in discrete batch production, while maximizing time-constrained throughput. Results have been concentrated on the class of homogeneous batch structures, i.e. batch structures with equal batch sizes for each process per cycle. In this paper heterogeneous batch structures are considered. By numerical examples, it is shown that heterogeneous batch structures can outperform the best result obtained by considering only homogeneous batch structures. Moreover integer programs are developed, which generate such solutions.