The goal of writing this thesis is to assess the state of nutrition and the state of fitness of fourth-grade students in primary education. By analyzing the state of nutrition and fitness, the current state of the measured characteristics will be determined, and guidelines will be made to improve them. Based on the aim and implementation of the research, a suitable sample of fourth-grade primary education students was selected from three elementary schools in Rijeka: "Pehlin", "Kozala" and "Gornja Vežica". 109 students participated in the examination, of which 42 were girls and 67 were boys. The eight morphological variables used to calculate the assessment of the nutritional status included: body weight, body height, BMI, back skin fold, upper arm skin fold, neck circumference, abdominal circumference and hip circumference. Also, the results of five tests were used to assess the students' fitness level: 30-second trunk lift, pull-up, squat to failure, lunge to failure, and long jump from a standing position. All tests were known to the students in advance and adapted to their age. When processing the data, a difference was determined between the students by gender and between the students of this study and the students of the 4th grade of the Primorsko-goranska from the unpublished data of Trajkovski (2023). It was concluded that the boys of this study have a slightly higher body mass and have a higher average height, and the girls have a slightly lower body mass and have a higher average height. The BMI of both boys and girls in this study is lower than the average value for that age, from which we can confirm that they do not belong to the category of overweight children. Although, from the results of this research we can conclude that the average value of the sum of skin folds shows that boys have a high percentage of body fat on average, and girls have an optimal percentage of body fat on average. Also, the WHR index shows that both boys and girls in the 4th grade are at risk of overweight and obesity in their further development. Comparing fitness abilities, we can conclude that both boys and girls have above-average fitness in the 30-second trunk lift test, in the squat to failure test, as well as in the diaper test to failure. In the pull-up and long jump tests, boys have below-average fitness and girls have above-average fitness. The conclusion of this thesis is that students should be monitored and checked regularly so that teachers have all the necessary information and can positively influence students, in order to improve their abilities and health.