Twenty children, presenting 66 proximal carious lesions in 60 primary molars, were selected to reveive composite resin tunnel restorations. Thirty of these teeth were expected to exfoliate within 6 months (group I); in the remaining 30 teeth exfoliation was expected within 1 year (group II). All teeth received tunnel preparations, which were then restored with a posterior composite resin. The restorations were evaluated after 6 months and after 1 year through each of the following methods: bitewing radiographic examination, clinical examination with a probe and mirror, and direct examination of proximal surfaces after tooth extraction. The occlusal portions of the restorations were considered to be excellent both after 6 months and 1 year. Radiographic examinations and direct examinations (performed after extraction of teeth) did not reveal the same percentages of secondary caries in the proximal portion of restorations. Fracture of the marginal crest reached 3% during the first 6 months, but fracture was absent during the subsequent 6 months.