This study examines the toughness and mechanical properties of biodegradable poly(ε-caprolactone) (PCL) with varying hydroxyapatite (HAP) content (0 – 30 wt%). Fracture toughness of HAP-filled PCL was also examined for the electrospun fibers using the essential work of fracture (EWF) concept. The electrospun fibers exhibited a diameter ranging from 200–500 nm and a combination of HAP particle sizes ranging from (50–100 nm) under the SEM. The tensile stress-strain behavior and fracture toughness of electrospun nanofibers were assessed using a nanoforce tensile tester. The electrospun system showed a substantial increase in plane-stress essential work of fracture in comparison to bulk specimens processed from pellets. Toughness decreased as HAP loading increased. The effect of simulated body fluid (SBF) on the mechanical properties was also studied. Mechanical properties including tensile strength and modulus were found to increase with HAP concentration in general. Compression molded electrospun nanofibers were spatially confined such that the tensile strength and stiffness of molded and spun fibers are remarkably higher than those from molded specimen of pellets.