The frequency of mobile phone (MP) use and the way students use them in school vary depending on the level of education, i.e., the age of the student, but also on the school, i.e., how it regulates its use. Many teachers stimulate the use of MPs during class, but by directing these activities to the topic being taught, knowing that an MP is an integral part of school supplies for a "digital native", both outside and inside the school. The purpose of this research was to determine the extent to which students used mobile phones in class and what their attitude was to the use of MPs during school activities and its impact on school performance. The research was designed as a cross-sectional study. The respondents were students of the Secondary Medical School in Belgrade, Zvezdara and represented a suitable sample, taken in one day in both teaching shifts, using an anonymous questionnaire filled in on a voluntary basis. A total of 152 students were included in the study, of which 114 (75.0%) were female. Most students were in the third grade of secondary school (45.4%). Respondents who expressed a higher degree of agreement with the claim that they used MPs in every class were significantly older (p=0.001) and had a significantly lower average grade (p=0.020). The statement that MPs had a negative impact on their concentration was agreed with by 59 students (38.8%), while 43 (28.3%) agreed that MPs distracted them from the important moments in class. The belief that MPs could contribute to the improvement of the teaching process quality was held by 126 (82.9%) respondents. Students who believed that MPs could contribute to the improvement of the teaching process quality agreed more with the claim that MPs had a negative impact on their attention (p<0.001) and concentration (p<0.001). Research has shown that almost a third of the students used MPs during class, even during every class, which was correlated with older age and lower average grades of students in the previous school year, as well as with the claim that they used it to suppress boredom. Younger respondents were more likely to believe that their mobile phone affected their concentration and success.