Objective: The purpose of this study was to evaluate the feasibility and performance of tunnel restorations placed in routine public dental service. Method and materials: A total of 420 small approximal lesions received tunnel restorations 12 general practitioners. Three hundred two restorations in 179 patients were available for evaluation after a minimum period of 24 months. The restorations were evaluated by modified US Public Health Service criteria. Results: After service periods up to 54 months, 57% of the restorations were found to be clinically and radiographically acceptable. The remainder had already been replaced or were assessed as unacceptable. High levels of carious activity and internal-type preparations resulted in the poorest prognosis. The success rates varied considerably among the operators, but these differences did not reach statistical significance. Conclusion: The indications for use of the tunnel restoration technique for the treatment of primary approximal lesions seem to be limited at present. Partial tunnel restorations may have a somewhat better prognosis than the internal tunnels, but high carious activity has a detrimental effect. Tunnel restorations may be considered for particularly cooperative patients with a low caries rate as a semipermanent treatment for small lesions.