A method for the determination of thin target PIXE efficiency from the measurements on pure thick targets was tested. The results of the method were compared with the results of two standard treatments, i.e. measurements of thin target PIXE efficiency on thin targets and calculation of this efficiency from the fundamental parameters. A better than ± 3% agreement with both methods usually applied was achieved for several elements from Ti to Pb and for protons of 1.5 MeV energy. The use of the proposed method seems to be encouraging also because of big cost and low durability of thin calibration standards.