Objectives: As data on the association of sugar consumption and dental caries in the industrialized countries give mixed results, we prospectively studied this association in 135 healthy Finnish children (71 boys, 64 girls). Methods: The dental health and oral hygiene of the children was first examined at the mean age (+/-SD) of 37.4 (+/-2.1) months and again at 73.7 (+/-2.6) months. On both occasions the parents were interviewed about the child's sweet intake and toothbrushing habits, and sucrose consumption was analyzed using 4-day food diaries. Results: The proportion of children with caries experience, enamel and dentin lesions combined, increased from 16% to 40%. Daily sucrose intake of children who developed caries by 6 years of age, whether expressed as absolute (g) or as relative (E%) amounts, was already higher at 3 years of age than that of children who stayed caries-free (P<0.05 and P<0.03, respectively). Furthermore, children who used sweets more than once a week at 3 years of age, consumed more sucrose 3 years later (P<0.01) than those who used sweets once a week or less. The proportion of children with a combination of a sweet intake more than once a week and visible plaque, increased (P<0.05) during the follow-up. The risk ratio of children with the combined risk habit at 3 years of age to develop carious lesions by 6 years of age was 1.7 compared to the rest of the children (95% confidence interval 0.9-3.0). Conclusions: We conclude that the manifestation of dental caries at 6 years of age seemed to be associated with a higher daily sucrose intake that had started already at 3 veers of age. Moreover, a combination of sweet intake more than once a week; and visible plaque at 3 years of age may be predictive of dental health 3 years later.