University rankings have become a prominent issue in an increasingly competitive world of higher education. Although a positive view of rankings is not unanimously shared, the number of meetings and references to ranking of higher education confirms a wide interest and attention to this phenomenon. This paper discusses the different instruments used for building university rankings and proposes a new methodology that involves simulation techniques allowing ranking universities in a robust way. The immediate benefit achieved is a reduction of the uncertainty associated with the assessment of a specific rank which is not representative of the real performance of the university, and an improvement of the quality assessment of composite indicators used to rank.