The aim of the paper was to investigate the effects of the addition of whey protein isolate (WPI) and whey protein concentrate (WPC80) on physicochemical properties of high-protein yoghurts. Changes in storage, loss moduli, phase angle values, flow behaviour and textural parameters were determined. Surface properties (roughness, contact angles) were also estimated. The properties of yoghurts depended on the preparation type and their concentration. The application of WPI resulted in accelerated gel formation in comparison with the yoghurts produced with WPC80. This technology is addressed to particular consumers who search for new foods to meet their daily protein requirements.