The role of mathematics in secondary-tertiary transition is subject to increasing analysis in several education contexts. We explore the longitudinal relationships among a standardized test used for assessing secondary school mathematics, high school final grades and the academic progress of a sample of Italian undergraduates. Results from regression analyses showed that the standardized test and high school final grades together are predictive both of the student's academic success in terms of Grade Point Average and of academic credits earned, whereas a more specific relationship emerged between the standardized test and the mathematics exam. This study provides findings on the importance of secondary school mathematics as a predictor of university performance, even in courses where mathematics is a service subject.