Rolling contact fatigue (RCF) is a significant problem in the rail industry as it causes rapid and difficult to detect cracks. Inclusions present in the material can have an adverse effect on the RCF life of rails. This study aims to discover the impact of the loading of rail steel in service on the inclusions present within the material. The work pays particular attention to the elongation and flattening of MnS inclusions and their contribution toward rail failure using a combination of micro-hardness measurements, inclusion analysis and focused ion beam analysis. The results indicate that the inclusions present in the material are considerably elongated by the loading of the rail in service and this may contribute to spontaneous cracking or assist in crack propagation.