Lichenoid lesions topographically related to resin-based composite restorations were observed in 17 patients. In eight of these the composite had been inserted to replace amalgam restorations that were topographically related to lichenoid lesions. The other nine had no history of lichenoid lesions. Total remission occurred in four cases after the composite had been replaced with gold inlays or gold-porcelain crowns, and partial remission has been observed in five patients so far. The use of posterior composite restorations is rapidly increasing, and possible side effects, such as erosive lichenoid lesions, caused by these restorations should be considered in the differential diagnosis of lesions in the oral mucosa.