The provision of quality transport services is a prerequisite for the creation of an efficient organization that can meet the expectations and requirements of both the enterprise itself and its customers. From the railway enterprise's point of view, it is necessary to pay attention to the increasingly demanding requirements of its customers in railway passenger transport. This article focuses on identifying defects in rail transport processes that negatively affect ordinary operations. One of the most serious bottlenecks affecting railway transport reliability is the train delay, which fundamentally affects the perception of railway transport. At the same time, it emphasizes the need to apply individual tools according to the DMAIC cycle in order to achieve continuous improvement. The aim of the implemented Six Sigma methodology in railway enterprise is disciplined application of statistical problem-solving tools to recognize the gaps in the transport process and set out individual steps for their gradual removal.