PURPOSE: The subject of this paper is to properly describe preanalytical faze mistakes as well as the impact they can have on specificity and validity of analysis results. It is important to point out the importance of every procedure during the work that is done, regardless of the inidivdual simplicity or rutine because mistakes happen even more often during those procedures. METHODS: In order to fulfill expectations that are set before it, laboratory diagnostics relies on strict rules inside the laboratory. Health workers are required to wear proper clothing and footwear to protect themselves as well as the others. Eating, drinking, smoking, having makeup or even wearing contact lenses is strictly forbidden. Rooms that are used for making analysis have to be airy, tidy and above all clean. Every patient analysis must me accompanied by a valid referral. Samples need to be correct and of quality for further analysis, otherwise it is discarded. After the work, gloves and the rest of contaminated material are tossed in special made containers and we wash and disinfect our hands and work area. RESULTS: After reading the researches made so far on this matter, I realized that more and more attention was directed on importance of preanalytics in treating patients in the last couple of years. The general idea is to continuously educate health workers and in that way try to prevent possible mistakes during the preanalytical faze. Using this method, the number of mistakes rather reduced. CONCLUSIONS: Mistakes are integral part of our lives. They are possible every time a human is included in an action. It is impossible to treat a patient without the occasional mistakes. It is important to recognize it, record it and admit it. That way we can learn from mistakes and gain new and positive work experiences.