In recent decades, orthorexia nervosa (ON) has increased presence in society. It is related with beliefs and attitudes towards eating and is characterized by an obsessive behavior toward heathy eating. The prevalence of ON has been reported by numerous researchers, with rates varying considerably according to the tool used to evaluate the same parameter. The aim of this study was to compare the prevalence of ON in a single population using two different questionnaires. The test for the diagnosis of orthorexia (ORTO-11-ES) assessment tool for orthorexia nervosa and the Düsseldorfer Ortorexie Skala (DOS-ES), constitute brief self-report assessment tools which measure the risk of suffering ON. A sample of 492 students from the University of Castilla la Mancha (Spain) participated in this study, of whom 43.1% were male and 56.9% were female. The findings show that, according to the DOS-ES, only 10.5% of students displayed ON whereas, with the ORTO-11-ES, the prevalence of ON increased to 25.2%. The tendency towards orthorexic behavior is more closely associated with the female gender. The Body Mass Index (BMI) had no influence on the tendency for ON. This study provides valuable information on the usefulness of both questionnaires and the possible limitations associated with the use of these tools in the general population.