Children and adolescents at school-age are most exposed to even the smallest nutritional errors. Therefore, it is important, especially during the period of development, to take care of wellbalanced diet and shape health-promoting nutritional habits. A rational diet in childhood and adolescence is the precondition of normal development and obtaining an optimum, genetically conditioned body structure, intellectual and emotional development and health. The objective of the presented study is analysis of the nutritional behaviours of Polish adolescents aged 12-17. The study covered junior high school adolescents aged 12-17 and their parents. The research instrument was a questionnaire form. The results of studies were subjected to statistical analysis. Completed questionnnaire forms were obtained from 9,360 schoolchildren and 6,950 parents. It was noted that the diet of adolescents in Poland is too rich in flour products (high glycemic index), sweets and animal fats, while it is too low in fish, fruits and products containing probiotics. Among Polish junior high school adolescents, 10.64% are obese and 5.79% overweight. Parents of the schoolchildren in the study not always objectively evaluate their nutritional status. Only 2% of parents of obese children provided compliant replies. These parents most often mentioned that their child had normal weight (49%) or is overweight (46%). Further education is necessary concerning adequate nutritional behaviours among childrenand adolescents in Poland.