Physical activity, after nutrition, is the most important factor determining health. Systematically undertaken physical activity significantly affects behaviour and results in the improvement of human health. The objective of the study was the evaluation of physical activity and state of nutrition among children attending elementary schools in opinions of children and their parents. The research tool was a questionnaire form designed by the authors. The questionnaire forms were addressed to children attending forms V and VI of elementary schools and to their parents. The study was conducted in May-June 2009 in schools selected in the area of two provinces: the city of Kalisz and the Kalisz Province. The results of studies were subject to statistical analysis. The following number of questionnaire forms were received: from children – 819, and from parents - 688. The majority of children likes and participates in PE classes at school. In addition, children are provided with physical activity during trainings outside school. More than a half of the respondents actively spend their free time; however, 1/5 of them spend their free time at computer. The results obtained confirmed the occurrence of excessive body mass (obesity or overweight) in approximately 20% of children. However, according to parents’ opinions only less than 10% of children weighed more than the standard.