Based on the theory of professional competition, this paper identifies and investigates four strategic options of supreme audit institutions (SAIs) through a case study of four Nordic national audit offices: a performance auditing strategy; a financial auditing strategy; a portfolio strategy; and a hybrid strategy. The analysis of the Nordic SAIs shows that while one SAI appears to have adopted a hybrid strategy, the portfolio strategy has been chosen by the three other SAIs, although with some variations in the portfolio. The paper concludes by discussing the implications of these strategic options for public sector auditing.