During the last thirty years, an increasing number of overweight and obese children has been noted. Overweight and obesity are problems which cause a lot of diseases and today generations find it difficult to cope with these problems. Because of the importance of this issue in life of both children and adults, results of many researches dealing with the same problem are included in this paper. The present study data have been collected based on the morphological characteristics (body height, body weight, body mass index, skin wrinkles, body fat) and the sport activities of school age children in the area of Primorsko-goranska county and the results of the research analysed. The research was conducted among "Pehlin" and "Kozala" elementary school children on the sample of 245 participants from 1st to 4th grade. It has been found that the children of elementary school age in Primorsko-goranska county have moderate body mass index, but percentage of fat in boys and girl urges for caution. Comparing boys and girls in the area of morphological features, it has been found that differences do not exist. It has been confirmed that children engaged in sports have better morphological features, lower body weight, lower body mass index, skin wrinkles and body fat compared to children who do not practice any sport. Based on this finding a kinesiological program of prevention has been created and the advices regarding the diet and free time of children given.