Non-destructive tests are of key importance as regards ensuring the safe operation of the railway track. Such tests enable the detection of discontinuities formed both during production and operation. However, due to their nature, non-destructive tests are characterised by certain limitations. Non-destructive tests are mostly indirect and the presence of discontinuities is inferred on the basis of specific physical phenomena. Through the detection and assessment of the nature of discontinuities, non-destructive testing methods provide information about the properties of objects subjected to examination. The article presents some of the methods (visual and ultrasonic tests) used in the examination of railway rails. The article also discusses unconventional testing methods, i.e. the method of magnetic flux leakage (MFL) and the measurement of the alternating current field.