A full polymeric optofluidic Fabry-Perot (FP) resonator with a high quality factor (Q) is proposed and tested. The device is based on multilayer optical polymeric films that act as high reflectivity interference mirrors. The all-polymeric laminated structure avoids any deposition or etching process, simplifying the fabrication procedure while retaining a high quality optical surface. The measured quality factor of the FP resonator is 3.03×104, and the finesse is 91 around 700 nm. The refractometric sensing properties have been measured, and a sensitivity of 314 nm/RIU with a limit of detection of 2.55×10-5RIU could be achieved. The device exhibits a very high figure of merit of 1.36×104RIU-1 that is comparable with the performance attainable with sensors based on photonic crystal and whispering gallery mode resonators.