Introduction. In the postoperative period, patients are exposed to increased pain, which affects their psychophysical condition. The degree of perceived post-operative pain is determined by a number of factors, including: preparation of the patient for surgery, type of personality, previous experience related to pain. The task of multidisciplinary treatment of pain is to eliminate physical suffering, improve mental comfort, as well as to assist in faster recovery and prevention of dangerous postoperative complications. Aim. The aim of the study was the attempt of a subjective assessment of postoperative pain. Material and methods. The research was conducted using the diagnostic survey method from July to October 2016. The study group consisted of 349 patients hospitalized in the Department of Cardiac Surgery of the Independent Public Clinical Hospital No. 2 in Szczecin. The research used the author's questionnaire. Results. A correlation between the mental state of patients before surgery and the intensity of postoperative pain was demonstrated. The strongest pain was felt on the 3-4th day, and then on the fi rst or second day after surgery while moving. The respondents indicated that the lowest intensity of pain was experienced on the fi fth day after surgery. Most of the respondents (194 people) felt nervousness and tension before the procedure. In the assessment of mental states, depression and diffi culties with concentration were declared by 58 subjects, while calmness and self-control reported by 94 people. Conclusions. 1) The mental state and preparation of patients for surgery signifi cantly affect the behaviour of patients after surgery. 2) Both correct treatment of post-operative pain, its systematic assessment, and the careful care of the nursing team, affect the positive image of the hospital in surveys and improve the quality of medical services provided. 3) It is advisable to conduct systematic training for nursing and medical staff in the fi eld of pain therapy in order to raise awareness of the adverse effects of acute pain.