PERISCOPE project assesses factors promoting or preventing obesity development in early age. A specific aim is to assess preschool children's physical activity habits in three different European countries. PERISCOPE has been implemented in 1094 children attending kindergartens in Denmark, Italy and Poland. The parents' and children's physical activity habits and attitudes assessed by a questionnaire filled by the parents. Overweight and obesity assessed by Cole's BMI cut-off points. Statistical analysis performed by χ(2) test and the test of proportion. Denmark shows the lowest rate (14.6 %) of overweight, followed by Poland (17.1%), while Italy shows the highest (21.2 %) (p < 0.0001). The Polish families show the highest rate of walking from home to kindergarten and back, followed by the Italians and, lastly, the Danish ones (p < 0.001). Almost all the Danish and Polish children, but only the 50.1 % of the Italians play outside (p < 0.001). During the weekdays, 34.9 % of Polish children, 22.2 % of Italians and 19.8 % of the Danish play outside more than one hour a day (p < 0.0001). During the weekend, 91.1 % of Polish children, 86.7 % of Danish children, but only 54.4 % of Italians play outside more than one hour (p < 0.0001). 53.5 % of Danish children, 31.9 % of Polish children, and 18.2 % of Italian ones practice sport (p < 0.0001). Danish children are the most active, the Polish are in the middle and the Italians are the least active. The difference in infrastructures (safety of walking streets, access to playgrounds/parks, etc.) can play an important role, in addition to cultural and social family characteristics, to the development of overweight.