The excessive mental workload in university students of Engineering careers is an important factor that affects their performance and their health and that, therefore, it is necessary to investigate. The purpose of this study was to examine the academic performance of students who develop their pre-professional practices, to see the impact of time dedication to work in companies and the excessive mental workload resulting in this dedicated time. For this, the industrial engineering students of a Peruvian university were taken as a study sample, focusing on determining the mental workload in university students, and how this influences their academic performance. This is evident when the students, in addition to carrying out their regular studies, must develop their pre-professional practices in companies in the industrial sector, for an average of two to three months, with a dedication of at least 30 h per week, with the expected consequences in their academic performance. For this, the impact of the practice was identified in a group of students attending the seventh and eighth academic semester during the period between 2018 and 2019. Subsequently, the number of credits carried by the students who do not develop pre practices is analyzed. professionals and a student who does carry professional practices and how this influence, in the variables of average grades, in the standardized coefficient of performance and in their cognitive abilities. Finally, the application of a mental workload assessment tool was included, which validated the hypothesis of the excessive mental workload that students have during that period and the negative impact it has on the performance of the majority of students involved. These results can be used to better balance the academic load of the students, so that they do not affect their studies as is the case so far.