The dental caries status of a population group is traditionally described by mean values of decayed, missing and filled teeth or surfaces (DMFT or S). Because of the limitations of the DMF values alone, additional measures of dental caries become important. A system of describing the pattern of dental caries attack hierarchically according to severity of caries was suggested by Poulsen & Horowitz (Community Dent Oral Epidemiol 1974;2:7-11). The purpose of the present study was to analyze caries data from a group of 3-6-year-old Chinese kindergarten children according to this hierarchical system, assess the hierarchical assumptions of the system with deciduous teeth and evaluate its usefulness as an additional caries description for a kindergarten population. As part of a longitudinal field trial, baseline caries data were collected from 452 children. Caries was registered by tooth surface without the use of radiographs. Each child was assigned to one of six mutually exclusive zones of increasing caries severity, from zone 0=caries free through zone 5, the most severe, assuming that once a child was classified into a given zone it automatically belonged to all zones of lesser severity (except zone 0). On the basis of the original six zones, 61% of the children were classified correctly according to the hierarchical concept, but different alternative models which merged one or more zones together demonstrated varying percentages of correct classification, the cariologically most acceptable one placing 83% correctly. For each age group there was a close correlation between mean dmfs and increasing severity. The hierarchical model provides a valuable additional description of the caries status in deciduous teeth and is consistent with professional and epidemiological knowledge of caries attack patterns.