The selection of students is a complex decision making process, in which multiple selection criteria often need to be considered and where subjectiveness and imprecision are usually present, resulting that fuzzy and imprecise data should be used. This paper formulates the student selection process as a multicriteria decision analysis problem, concretely as a ranking problem, by using the ELECTRE III methodology to construct a fuzzy outranking relation, and then a genetic algorithm to exploit it and to obtain a ranking in decreasing order of preference. An empirical study of a real selection problem in the Universidad de Occidente in Mexico is presented. After performing calculations and obtaining the final ranking of compared alternatives, a sensitivity analysis was carried out. The study was supported with a new decision aid system for rank a finite set of multicriteria alternatives.