The use of fiber-reinforced posts in post-endodontic rebuildings, adhesively luted into root canal, reached a high clinical safety in the last ten years. Objectives: the purpose of this in vitro study is to evaluate if different surface pretreatments are able to increase the composite-to-quartz fiber post adhesion. Methods: 24 quartz fiber posts ( Endolightpost, RTD ), have been subjected to different surface pretreatment and subdivided into 6 groups: 1) no surface treatment ( as control ). 2) post sandblasting. 3) use of silane ( Calibra, Dentslpy ). 4) lightcuring of single-bottle adhesive ( One Step Plus, Bisco ) onto posts surface. 5) etching of posts with hydrofluoric acid 9.6 % ( Pulpdent ) for 15 sec. 6) etching of post with hydrofluoric acid 9.6 % + Lightcuring of single-bottle adhesive. A composite-made core has been built onto each post by using the same plastic form ( Composipost Core Form, RTD ), and slices 2.5 mm thick have been obtained with a diamond wheel ( Leitz 1600 ). Slices have been subjected to pull-out test with Instron Machine. Results: 1) no treatment: 230 N; 13.77 MPa. 2) use of adhesive: 258 N; 15.00 MPa. 3) sandblasting: 266 N; 15.46 MPa. 4) use of silane: 283 N; 16.45 MPa. 5) etching with hydrofluoric acid: 299 N; 17.38 MPa. 6) etching + adhesive: 412 N; 23.95 MPa. Conclusions: by using adhesives layered onto the post, sandblasting or surface silanizing, only poor results in increasing the composite-to-quartz fiber posts adhesion are obtained. Treating posts with hydrofluoric acid 9.6 % for 15 sec + lightcuring a single-bottle adhesive onto the etched surface, lead to much better results, with a real improvement of the composite-to-quartz posts adhesion.