This study compared different groups yearly based on the different annual quota of Physical Education (PE) classes in anthropometric parameters, physical fitness tests, and grades achievements. The study included adolescents from 14 to 18 years of age, at the Croatian Industrial School in Slavonski Brod. They were 225 participants in the 2015-2016 academic year, 213 in 2016-2017, 200 in 2017-2018, and 318 in 2017-2018. Groups were determined yearly by the different annual quota of PE classes (1 or 2 per week) in the teaching program. Anthropometric measures (body height, body weight, BMI), physical fitness tests (standing long jump, sit-ups, run for 1000 m), grade in the PE class, and the general achievement grade at the end of the school year were conducted. Data collected from the 2015-2016 until the 2018-2019 academic year. Analysis of variance (ANOVA) was used to assess the differences between groups for each school year separately. Results for sit-ups and run for 1000 m test in 2015-2016, BMI in 2018-2019, and the grade of PE class in 2017-2018 and 2018-2019 academic year indicated significant differences between groups (p<0.05). The groups with 2 PE classes per week were made better results compared to the groups with 1 PE class. Therefore, increasing the number of PE classes per week should be necessary for achieving the positive, beneficial, physical, and mental outcomes of Physical Education.