A practical fault diagnosis system based on combinational Automatic Test Pattern generation (A TPG) and fault simulation is described. Our fault diagnosis system deals with conventional stuck-at and bridging faults, as well as measurements condition dependent (MCI)) faults in order lo diagnose those faults causing different behavior by measurement condition such as supply voltage and temperature, using single stuck-at based diagnosis techniques. experimental results with practical very deep submicron (VDSM) LSI circuits shows that practical defective chip an be sufficiently diagnosed using our diagnostic algorithm nd newly proposed MCD fault model.