The study aimed to measure the level of anxiety towards mathematics in high school students and if they differs by gender and institution. For this, the scale designed by Murioz-Cantero and Mato-Vazquez (2007) was applied to 536 Mexican students from three different institutions in the public sector. This instrument is divided into five factors: anxiety towards the evaluation, towards the temporality, towards the understanding of the problems, towards the numbers and the mathematical operations and towards real life situations. The data matrix was analyzed using the Cronbach's alpha coefficient to validate its consistency, from which a very acceptable value of .932 was obtained. The analysis confirmed that the data matrix is not an identity matrix and presents acceptable correlations between variables, confirming the extraction of five factors that explain 63.38 % of total assimilable variance. In addition, the ANOVA test was calculated with the F statistic and its significance to prove the hypothesis of equality of means. A significant difference of means by gender was found in four of the five factors. Only anxiety towards real-life mathematical situations had no significant difference in means. Otherwise, the academic institution variable show difference between groups only in anxiety towards real-life mathematical situation. The Levene statistic was calculated for both variables to prove the hypothesis of equality of population variances. The gender variable presented equality of population variances in the five factors. The institution variable had not equality in population variances in anxiety towards mathematical problems comprehension and anxiety towards real-life mathematical situation.