Purpose: This paper aims to compare the students enrolled to a three-year undergraduate, bachelor degree on Security of Computer Systems and Networks, offered in traditional, classroom fashion as well as online at the University of Milan (Italy). Its main purposes are to estimate the main characteristics of the two different student populations addressed (i.e. online vs classroom students) to understand if an online version of an already existing traditional university degree allows to extend the enrollment of students; and to evaluate the effectiveness of the e-learning approach adopted, comparing performance of the two student populations. The study aims to supply a significant case study, based on a real experience more than 10 years long. Design/methodology/approach: The paper is based on the statistical interpretation of a huge amount of data, collected during the overall life of Sicurezza dei Sistemi e delle Reti Informatiche (SSRI) online, regarding student age, income, grades obtained in exams and after final dissertation and graduation time. Findings: The paper allows to conclude that the online student population has very limited overlap with the classroom one, which means that the online version of an already existing degree can definitely enlarge the student enrollment and reach older students; and a carefully designed e-learning environment allows committed online students to obtain results comparable when not better than the ones of classroom students. Research limitations/implications The study refers to a single, specific degree in computer science and technology; thus, it may lack generalizability. Similar experiences in other areas could be useful. Originality/value: This paper fulfills an identified need to study how e-learning can be successfully applied to already existing traditional university degrees.