Adhesion between electrospun polycaprolactone (PCL) fibers was directly measured in a cross-cylinder geometry using a nanoforce tensile tester. The surface roughness of fibers was determined by an atomic force microscope (AFM), and the structural factors were characterized by differential scanning calorimeter (DSC) and wide-angle X-ray diffraction (WAXD). "Pull-off" force was found to be in the order of 10(-6) N, and the adhesion energy was 190 +/- 7 mJ/m(2). Adhesion increases with decreasing fiber radius. The experimental data are analyzed by the classical Johnson-Kendall-Roberts (JKR) contact mechanics model. The study provides fruitful insights into future development of bio-inspired adhesives and devices.