The paper presents an experimental investigation of elastic wave propagation in a self-drilling hollow bar system, which is commonly used in geotechnical industry as the element of grouted ground anchors and soil nails. The single self-drilling hollow bar and self-drilling system of two bars connected by a coupler were considered. Longitudinal waves were excited at one end of the bar and registered at both ends, by means of PZT plate transducers. Additionally, in the case of connected bars, the transducer was also located at the coupler. The main aim of the study was to analyse the wave attenuation because of discontinuities in the form of mounting connections occurring along the bar length. The differences in wave propagation signals registered at single bar and the system of two bars were indicated and discussed.