Polycapillary optics are becoming increasingly important in XRD technology. When an X-ray beam strikes polycapillaries at angles smaller than the Fresnel's (the "critical angle"), the total external reflection regime arises and radiation is transmitted with high efficiency and low losses. Therefore, using polycapillary optics with a suitable shape, it is possible to concentrate and focus the X-ray radiation or to change a divergent X-ray beam into a quasi-parallel one. Such characteristics make polycapillary optics a valuable instrument in the development of up-to-date XRD apparata. Due to the small value of the critical angle, the main problem in using polycapillary optics is related to choosing the best alignment with respect to the source. Using a Huber four-circle diffractometer we were able to develop a suitable procedure for fast and precise alignment of a polycapillary lens in front of a Cu X-ray tube. When we reached the best alignment by means of a fluorescent screen, we were able both to observe the focussing effect and to take a set of photos with a Polaroid-Land film holder. The beam diameter at the polycapillary entrance was about 8 mm,while the diameter of the spot size at the focal point was less than 2 mm. Using a scintillation detector we evaluated an increase of about 27 in the local density of the X-ray beam. These results confirm the advantages of polycapillary condensing lenses and encourage their use in several XRD areas, such as micro-diffraction, residual stress analysis, grazing incidence diffraction measurements, etc.