Abstract This study examines the moderating effect of tolerance for ambiguity, a personality variable, on the relation between management accounting systems (MAS) design and managerial performance. MAS design was defined in terms of the extent to which managers» use of broad scope MAS information for managerial decision making. The responses of 63 managers, drawn from a cross-section of Australian manufacturing companies, to a questionnaire survey were analysed by using a multiple regression technique. The results indicate that the use of broad scope MAS information interact with tolerance for ambiguity to affect managerial performance. The results indicate that an appropriate «fit» between manager's personality variable of tolerance for ambiguity and the extent of use of broad scope MAS information for managerial decisions will lead to improved managerial performance.