In this study the occlusal characteristics of the deciduous dentition in a sample of young children were investigated to determine whether consensual trends exists, and if the occlusal characteristics in the primary dentition may be considered as acceptable predictors for occlusal relationships in the permanent dentition. Four hundred and seven boys and three hundred and eighty-two girls aged 4-6 years participated in the epidemiological study. Recording of the occlusal traits was made according to the method described by the Fédération Dentaire Internationale in 1973, adapted to the primary dentition. Lack of space was frequent (24 per cent in the upper anterior segments), as well as lateral crossbites (16 per cent), excessive overjet of 6 mm or more (6 per cent), Class II relationships (26 per cent) and anterior open bites (37.4 per cent). Obvious similarities could be seen with other investigations on occlusal traits of the primary dentition of Caucasian children. Cross-comparison with available data suggest that the development of the occlusion is a continuum for many aspects, with most of the major occlusal trends characterizing the permanent dentition in Europoid populations detectable at early stages. The striking difference in the primary dentition was the much higher prevalence of anterior open bites: this is the only figure expected to decrease dramatically in the permanent dentition. With due reservation inherent to the nature of epidemiological data on malocclusion and their interpretation, it is concluded that, provided the patient's cooperation is satisfactory, early attention may be given to malocclusion, but should mainly be focused on lateral crossbites and sagittal malrelationships.