The aim of the two-year study was to compare the efficacy of two caries prevention approaches in preschool children basing on oral hygiene and dentition. In addition, parents were polled in order to evaluate their attitude towards prophylaxis and treatment of caries and to obtain their opinion on the programme. The first year of the study focused on 4 and 6-year-old children in whom two preventive approaches were applied, i.e. daily toothbrushing under supervision of trained (1) teacher or (2) parents. Since the results of the second approach were unsatisfactory, approach No. 1 was adopted during the second year of study in 3, 4, 5, and 6-year-old children. All children were supplied with a low-fluoride toothpaste and the toothbrush was replaced every three months. Approach No. 1 significantly reduced Pl.I by 89% in 4-year-old children, decreased caries progression in primary and permanent dentition, and reduced the number of filled teeth. A more prominent effect of oral hygiene vs. diet on caries progression in primary teeth was documented. Efficacy of approach No. 2 did not meet expectations.