A special model for dental care in pre-school children was used in a small clinic in the county of Blekinge in southern Sweden. The model is based on screening of caries risk performed by a dental assistant before the caries attack. Any single risk factor or risk behavior in pre-school children was considered. The aim was to 1) evaluate the dental assistant's selection of caries risk children up to the age of three years, 2) compare dental health variables in 4 yr olds in the test clinic with those for the whole county in 1994 and 3) compare time spent by the dentist and the dental assistant in the test clinic and in the whole county per child up to the age of four. 102 children participated. One specially trained dental assistant screened all children using background factors combined with clinical examinations at ages 1, 2 and 3. Eighty-two children participated each year from one year. A systematized form for questioning the parents was used. Individual caries prevention was given including fluoride and antimicrobial treatments as well as fissure sealants in primary molars at caries risk. The proportion of children with caries lesions at four years and a caries risk assessment up to the age of two was 1.0 (sensitivity). The proportion of children with no caries lesions at four years and no caries risk assessment at year two was 0.7 (specificity). The most frequent risk factors found at 2 yrs were frequency order: lack of oral hygiene (visible plaque), deep fissures in molars and frequent intakes of sweet drinks. The proportion of children with no caries lesions at 4 yrs of age in the test clinic was 92.9% compared to a county mean of 76.4%. In the group of children where a risk assessment was made each year from one year the proportion of caries free children was 96.3%. The total time spent per child in the test clinic was 22 minutes more than the county mean. However, dentist's time, excluding assistance, was 28 minutes less in the test clinic. The results suggest that the model used for caries prevention in pre-school children is cost-effective, and that dental health can be remarkably improved.