The chapter assumes organisational culture, which is most valuable resource of organisation, cannot often be treated coherently by managers in change management that ultimately leads to ineffectiveness and failure. In order to make organisational culture a powerful managerial instrument in change management resulting in high organisational performance the chapter proceeds through the following sequence. At first, it elaborates chief characteristics of organisational culture in order to underline its value; secondly, portrays significance of interpreting and managing organisational milieu; thirdly, emphasises necessity and difficulty of organisational culture change; and then offers a systems approach called two strands model of soft systems methodology to improve the effect of corporate culture on organisational performance. The last part describes the methodology in depth and shows how it is applied to a private hospital that generates its improved version dealing with the major issue of open, full and equal participation in organisational culture change management.