This paper presents a case study to adjust the product group at ‘an SME (small and medium size enterprise) pharmaceutical company’. The company produces an excessive amount of different products using its maximum capacity, which causes inefficiency. Considering the fact that the company is growing fast, it needs to adjust its product group by removing inefficient products. In order to help the company, we carried out simulation to find out bottleneck process and after that we also conducted hierarchical clustering analysis to figure out which product causes inefficiency most severely, using three indicators consisting of the bottleneck contribution, sales, and contribution margins. Applying the ExtendSim simulation with the clustering analysis result, we substituted ‘better (i.e., causing less inefficiency) products’for the problematic ones and observed the increases in the sales and profits at the company in various scenarios. The paper shows how we can derive managerial implications useful for the SME’s production planning from these approaches.