The objective of this study was to assess dental caries and its relation to plaque, tooth brushing habit and past dental attendance, and to determine the caries pattern in primary dentition of preschool children. One hundred and three, 5-year-old children, from preschool nurseries in Al-Kharj, Kingdom of Saudi Arabia were studied in 1994. The World Health Organization criteria was used to determine caries. Only 16.5% were caries free. The mean decayed missing filled teeth (dmft) was 7.1, and by excluding caries free children it was 8.5. The decay component of dmft was predominant (82%). Almost 90% of the children had plaque present on their teeth and one-third never brushed their teeth while two-thirds had never been to a dentist. All children who never brushed their teeth had plaque and caries. Molars were the teeth, which were most frequently carious, and caries among all teeth was always bilateral. There was high prevalence of untreated caries and high dental needs with concomitant poor dental health among these preschool children.