Aim: Shaping should be complemented by antiseptic solution. These are often delivered using a needle and syringe. But apical penetration of the irrigation solution is of only 1 mm beyond its tip. The aim of our study was to evaluate the influence of the apical preparation on the penetration depth of some needles. Methodology: 24 teeth were divided randomly into two groups and prepared in continuous rotation (350 rpm) with Revo-S 1 or ProTaper 1 to sizes AS 30, 35 and 40 and F1, F2 and F3 respectively. Four types of endodontic needles were used. Three sizes of stainless steel needles: Peer review under responsibility of Società Italiana di Endodonzia.