Purpose: This study was carried out to investigate the effect of thermocycling on fiber dowels using different adhesive systems. Materials and Methods: 60 human teeth were selected. Decoronation, followed by canal enlargement then obturation was done. The teeth were mounted in acrylic and the posts of the sixty samples were luted with the three different adhesive approach 1) Total etch 2) Self etch 3) Self adhesive. All the specimens were subjected to thermocycling between 5C° to 55°C for 500, 1000 and 2000 cycles. The root of each tooth was sectioned into 3 samples : cervical, middle, apical ones ,to undergo the push out test using a universal testing machine. Results: self adhesive cement group recorded highest push out bond strength mean value. non-cycled control group recorded higher push out bond strength mean value followed by 500 cycle group then 1000 cycle group then 2000 cycle group. The cervical region recorded lowest push out bond strength mean value followed by middle region then the apical region. Conclusion: Thermocycling drastically decreased the bond strength of all the luted posts irrespective of the adhesive.