This paper describes measurements of fiber loss and splice loss by backward Rayleigh scattering in fibers. Fiber loss measuring accuracy less than0.04 dB is obtained, and the repeatability is very good in comparison with conventional cut-back method. For splice loss measurement, the measuring accuracy is the same as the above. It is found that the splice loss measured by the backscatter method is different from the true value for fibers with different Rayleigh-scattering losses. To obtain the true value, several correction method for the measured value are proposed. Application of the backscatter method to fault location reveals that even an 8.6 km distant fiber end-face without Fresnel reflection can be discriminated.