This chapter focuses on the vitiating factors in a contract, namely those that can render a contract void ab initio or voidable (the distinction between void and voidable contracts is discussed). These include misrepresentation, mistake, duress, undue influence, unconscionable bargains, and illegality and public policy. and fairness in the law of contract. In this respect, vitiating factors tend to focus on the latter (with the former constituting, at most, just one conception of fairness, amongst others). However, because of the consequent danger that contracts might be unravelled unnecessarily by the application of such factors, there is a need for doctrinal as well as conceptual clarity. This article focuses, first, on key (and Vitiating factors in a contract are those factors the existence of (any of) which will cripple or invalidate the contract. Vitiating elements of contract such as mistake, duress, misrepresentation, undue influence and illegality, are determinants of the validity of a contract. They are the various factors which can affect the