Objectives: To investigate the effects of pretreatment (silanization) on bond strengths between 3 different types of fiber posts and 4 resin cements, respectively. Method and Materials: Prefabricated quartz-fiber (Unicore Post, Ultradent) and prefabricated glass-fiber (FRC Postec, Ivoclar Vivadent) posts with a cross-linked polymer matrix and individually formed glass-fiber posts with an interpenetrating polymer network (IPN Post, Stick Tech) (n = 160 each) were inserted into resin composite disks (2 mm thick) using the following resin cements and silane solutions: Panavia F/Porcelain Bond Activator (Kuraray), PermaFlo DC/Silane (Ultradent), Variolink II/Monobond S (Ivoclar Vivadent) and RelyX Unicem/Espe Sil (3M Espe). Nonsilanated posts served as controls. The push-out bond strengths were determined before (n = 10) and after (n = 10) thermocycling (2,000 cycles, 5°C to 55°C, dwelling time 30 seconds). Results: Bond strengths (mean [SD]) were significantly affected by the resin cement (P .001), the pretreatment (P .001), and the type of post (P .001), but not by thermocycling (P = .955, 4-way ANOVA). The IPN post demonstrated significantly higher bond strengths compared to the other posts (P .05; Tukey B). Silanization significantly increased bond strengths (15.2 [5.2] MPa) compared to those of the control groups (13.9 [4.9] MPa). Conclusion: The type of fiber post revealed a significant influence on bond strengths, whereas the effects of silanization appeared to be clinically negligible. Schlagwörter: fiber post, push-out bond strengths, silane, thermocycling