A pilot study was initiated to prove the effectivity of a prophylaxis programme for small groups of preschool children. A total number of 190 children was examined twice a year at the Dental School of Erlangen. The dental examination included df-s index and plaque index according to Quigley-Hein. Tooth cleaning was performed in small groups under professional supervision. Professional plaque removal and local fluoridation concluded each session. Twice a year the parents were offered oral hygiene instructions and informed about the relationship between sugar and caries. After two years the dfs-values were significantly lower in the test group than in the control group. Mean dfs scores ranged from 1.9 for the experimental to 3.8 for the control group. These comparatively low recordings--as against other investigations--may be due to the relatively high social standing of the children.