The aim of this research is to explore section 172 of the Companies Act 2006 which replaces the duty to act in the best interest of company .However, the meaning of s.172 is unhelpfully vague and uncertain clarity is required to provide certainty regarding the obligations of directors under s.172. In terms of research method, this research covers three areas namely;(1)- directors' fiduciary duty pre Companies Act 2006 -the `duty to act bona fide` in the best interests of company (2)- The new directors' duty as set out in s.172 of the Companies Act 2006, to promote the success of the company for the interests of members as whole. And the uncertainty which surrounds how s.172 relates to directors, shareholders and stakeholders (3)- Whether greater statutory provision is needed to clarify and improve s.172 to clarify the duty relating to companies' governance. To carry out the above research, all available relevant literature on this topic was considered, focusing on case law material, judicial statements, journal articles and legislation.