As rock bolts are grouted into e.g. cement or epoxy, only one end is accessible for the analytical technique in question, ultrasonic methods are being considered valuable nondestructive techniques for estimating the bolt integrity. The conventional acoustoelastic ultrasonic technique for deducing the axial loading of prestressed bolts is based on variations in the time-of-flight of a single longitudinal bulk wave with loading. A main drawback of this mono-wave technique is the required pre-knowledge of the initial bolt length and the initial loading condition. The bi-wave method on the other hand allows the axial load in the stressed state to be calculated from the time-of-flight ratio of two different wave types, without preknowledge of measurement in the unstressed state. Commercial piezoelectric probes exist that simultaneously generate and detect both longitudinal and transverse bulk waves, and the bi-wave technique has successfully been used for deducing the axial load of 50-215 mm long bolts. Piezoelectric transducers, however, require an intimate contact with the bolt end why errors rise from various surface conditions and couplant properties. The primary advantage of EMAT transducers over piezoelectric transducers is the ultrasonic wave generation and detection through electromagnetic forces, without requirements for intimate contact with the bolt end. The main drawback of the EMAT systems is; however, the generally low signal-to-noise ratio compared to piezoelectric transducers. Currently no commercial EMAT probe exists for bi-wave applications; however, an EMAT bi-wave prototype equipment has proven capable to measure the axial load condition of bolts with lengths up to 500 mm.