Caries in deciduous teeth of 309 children was analyzed between 1999 and 2006 in 6-years-old and younger children with early childhood caries in the Clinic of Pediatric Dentistry of the university of Jena. With increasing age of the children caries decay amounted from 7 up to 13 dmft. Between 2 and 4 teeth had to be extracted. Summarizing, children are most likely to develop caries if mutans streptococci are present at an early age, although this may be partly compensated by other factors such as good oral hygiene and non cariogenic diet. Diet and oral hygiene may internet so that if there is a balance of good habits by way of maintaining good plaque control and bad habits by way of having a cariogenic diet, the development of caries can be controlled.