The paper presents the results of Particle Image Velocimetry (PIV) measurements of the velocity field of a Newtonian fluid in a mixing tank equipped with a PMT type impeller. The results are presented in the form of the velocity vectors, profiles and maps and compared with available data in the literature for the corresponding system, obtained from Laser Doppler Anemometry (LDA) measurements. A good qualitative agreement of the results was found. In the flow one primary and two secondary circulation loops were observed. The PMT type impeller produced a typical axial-radial circulation of the liquid in the vessel. The value of the circulation flow number, KC, was calculated.