X-ray powder diffraction is a method, based on X-ray diffraction on crystalline solids. Each crystalline phase has a unique powder diffractogram, which enables us to perform qualitative analysis. In my research, I have analyzed sixteen different patterns of painkillers. I prepared the samples appropriately for recording with powder X-ray diffractometer and processed the recorded data qualitatively with computer programs. The main purpose was to identify active pharmaceutical ingredient and excipients in painkillers. I was interested in the differences between medicines with the same active pharmaceutical ingredient and whether there were any additional substances not listed in the instructions for proper use of medicines. With X'Pert HighScore Plus, I compared the powder diffraction patterns with each other and obtained data on the crystallinity or presence of the amorphous phase by analysis. With the CSM program, I found that in the samples analyzed, most of the diffraction patterns belong to the active pharmaceutical ingredient and only a small proportion to the excipients. As a result, I have found that powder diffraction patterns of painkillers containing the same active pharmaceutical ingredient are very similar. I was unable to identify some of the samples, as they were very poorly crystallized or amorphous. Comparison of the established composition of the samples with the declaration on the medicinal products showed an agreement as expected.