Introduction: Colonoscopy is an endoscopic examination of the large intestine (colon) and the final part of the small intestine. Despite its widespread use, it is accompanied by shame, discomfort, and sometimes pain. Anxiety occurs in most patients before the examination, while discomfort and pain mostly occur during the examination. All these factors have a key influence on the complexity and the outcome of the examination, as well as the speed of the patient's recovery after the examination. Nurses play an important role in this process; they help prepare patients using their extensive knowledge, experience, and expertise. A key factor in this process is psychological preparation, which primarily affects the patient's well-being and thus helps make the examination more efficient and its outcome more favourable. Psychological preparation is based on several pieces of information that must be collected by a nurse prior to the procedure. Purpose: The purpose of this thesis is to present the importance of good psychological preparation of colonoscopy patients and its impact on the outcome of the examination, while also emphasizing the role of the nurse in the process of colonoscopy. Methodology: This diploma thesis uses a descriptive method and consists of an overview of peer-reviewed literature, which can be found in the following databases: Academic Search Complete, Cinahl, COBIB.SI, Google Scholar, Medline and Science Direct. Results: The results define psychological preparation and show why it is important before, during and after the process of colonoscopy. The elements of psychological preparation and the ways in which it can be achieved are presented, alongside with the different techniques that have proven to be effective. The role of the nurse in the pre-procedure preparation, the preparation of the patient, and the implementation, which all affect the outcome of the examination, are also described in detail. Discussion and Conclusion: A review of relevant literature has shown that extensive research has been done on the topic of techniques that relax the patient. As anxiety and fear are two of the main reasons why a patient is more sensitive to pain during the examination, it is important that psychological preparation also includes techniques that address this issue. Nurses must be well informed about the patient's condition before the examination, as this helps them understand the patient and choose the appropriate techniques to make it easier for the patient to cope with the examination.