Purpose: To assess caries prevalence and periodontal condition in adolescents in Poland and investigate the factors related to oral health. Materials and Methods: A national survey was carried out among 615 15-year-olds of both sexes living in urban and rural areas. Subjects were selected via cluster sampling. The mean DMFT and its components, the tooth distribution pattern of caries and percentage of subjects with gingival bleeding and gingival pockets were analysed. The information regarding sociodemographic, oral hygiene and nutritional variables was collected via questionnaire to evaluate their relationships with caries and periodontal parameters. The t-test, bivariate and multivariate logistic analyses were conducted to evaluate the differences and dependent variables of caries prevalence and gingivitis. Results: Caries prevalence was 94.0%, and DMFT was 5.75 ± 3.74. Higher DMFT, DT and MT values were found in rural areas. 50% of the subjects carried about 75% of the total caries burden. Severe caries (DMFT ≥7) was associated with toothbrushing less than twice a day, not using a fluoridated dentifrice, frequent consumption of snacks and absence of pit-and-fissure sealants. The prevalence of gingival bleeding was 37.4% and shallow pockets 2.8%, which were higher in males and rural areas. Gingival bleeding was associated with toothbrushing less than a twice a day, not using dental floss and consumption of fresh fruits and vegetables less than once a week. Conclusion: The prevalence of oral diseases in Poland is very high. Additional strategies must be implemented to promote oral health early on to improve oral hygiene practices and nutritional habits. Keywords: dietary and oral hygiene practices, DMFT, gingival bleeding, Poland, 15-year-olds