The study of Mathematics has been and is still a source of frustration and anxiety for a large number of students. The purpose of this study was to inquire systematically upon levels of test anxiety through behavioral and physiological procedures before and after a Math test, in 205 senior high school students. Academic worries were assessed by means of a computerized task based on the emotional version of the Stroop paradigm designed ex profeso to measure school anxiety (Hernández-Pozo, Macías & Torres, 2004). The Stroop task was administered, along with recordings of blood pressure and pulse, before and after the first Math test of the course. Academic general scores were inverse to the behavioral anxiety level, however the best Math scores were associated to middle levels of behavioral anxiety. Contradictory findings between academic performance in Math and global score, and the apparent lack of gender difference in anxiety measured through behavioral procedures suggests the need to review the generality of previous assertions relating academic performance inversely with levels of anxiety of high school students.