This study analyses two different shelf replenishment methods for a leading German drugstore chain and proposes a conversion from the commodity group-based shelf replenishment approach towards a shelf replenishment process based on sales data. For that the sales data of a sample retailer was collected for one quarter and analysed to determine a suitable commodity group for the simulation project. In a next step, the shelf space and the demand distribution for 106 SKUs was determined and provided the input for the simulation model to determine potential benefits of a sales data-based shelf replenishment process. We were able to show that a shelf replenishment process based on sales data provides ample opportunity for retailers to improve one of their most costly business processes.