An experimental investigation of interface fracture in high strength concrete is reported. An attempt has been made to study the influence of strength of mortar, type of aggregate and its roughness on interface fracture properties. The parameters include load-CMOD variations, tensile strength, and fracture energy of the interface. Stiffness, compliance and ductility factors of the composite specimens have been evaluated in Mode-I loading. The fracture energy increases as the roughness of the aggregate surface increases. The stiffness of the composite specimen increases as the roughness of the aggregate surface increases. The ductility factor (i.e. the fracture energy per unit of peak load) decreases as the surface area of the interface increases in sandwiched composite specimens in Mode-I failure, whereas it increases with the interface area in composite specimens with mortar cast against rough concrete aggregates. The interface exhibits brittle behavior with catastrophic failure indicating the application of LEFM to the interface.