The present investigation was carried out 1) to identify subjects with juvenile periodontitis (JP) in a group of schoolchildren from a community with a high prevalence of periodontal diseases and with no access to preventive dental care, and 2) to study the clinical features of the disease and the progression pattern during a period of 1 yr, and the relationship of JP to clinical periodontal parameters. The periodontal condition of a group of 502 Iraqi schoolchildren (260 girls and 242 boys) was assessed radiographically and clinically at baseline. Children showing > or = 3 mm arc-shaped angular radiographic bone loss at the proximal surfaces of two or more first molars and who showed clinical attachment loss at the same sites were regarded as JP patients. A second group of children with no signs of JP were randomly chosen from the study material. One year later, the JP and the non-JP groups were re-examined radiographically and clinically to assess plaque, gingivitis and presence of calculus. The results showed that nine children (1.8%) had JP. The ratio of girls to boys was 3.5:1, and of localized to generalized forms 2:1. Mesial surfaces of first molars were more often affected than distal surfaces. Clinical assessments showed a more profound loss than was depicted radiographically. All JP patients exhibited evidence of periodontal disease progression during the following year. There were no differences between JP and non-JP children with respect to gingival inflammation, dental plaque, or calculus deposits on teeth.(ABSTRACT TRUNCATED AT 250 WORDS)