The aim of the research was to conduct a longitudinal study of motor and cardiorespiratory fitness of 5th to 7th grade elementary male and female pupils in the period from 2005 to 2020. The pupils (1649) were divided into 3 generation groups: the older (2005–2009), the middle (2010–2015) and the younger group (2016 – 2020). There is a noticeable decrease in flexibility among all pupils and grades of younger generations. Results indicate poorer performance of younger gener ation of 5th graders in speed and power. The 7th grade female pupils who were tested in the 2015 – 2020 period, showed a significant decline in all motor and cardiorespiratory fitness compared to the other two generation groups, except for upper body power. Every four years, an evaluation of test results should be carried out so that each Physical Education teacher in a particular school can accurately compare and standardise the obtained values.