A study has been made of the influence of sulphide inclusions and microstructural parameters on the ductility and failure of low alloy steels with different stress state patterns. Experiments on determining ductility were carried out with the application of high hydrostatic pressure. The results of metallographic and microfractographic investigations are discussed. With mild stress state patterns, steels with an increased sulphur content can have the same ductility as clean steels.