INTRODUCTION. Pressure ulcers are an important medical and social problem. Numerous scientific research projects focus on epidemiology, etiology, pathogenesis, prevention and treatment of pressure ulcers. However, many aspects still remain obscure, including the effect of some selected factors on formation and development of pressure ulcers, as well as safe and cost-effective methods of their prevention and treatment. Pressure ulcers are a source of pain. They reduce patients' quality of life, extend duration of hospitalization and account for increased costs of care. Early identification of high-risk patients and appropriate preventive measures are among priorities. And presence of pressure ulcers calls for a comprehensive and modern treatment. Both prophylaxis and treatment of pressure ulcers require team work, in which a significant role is played by nurses. OBJECTIVE. Assessment of risk and incidence of pressure ulcers in patients hospitalized in medical treatment wards was the principal purpose of the study. MATERIALS AND METHODS. 4146 inpatients of two medical treatment wards of one of hospitals in Krakow (Poland) treated between January 1st, 2014 and December 31st, 2014 were initially recruited. Following the preliminary analysis, 802 patients dropped out, as they were repeatedly hospitalized in the study period. Finally, 3344 patients were qualified. All of them w ; ere hospitalized for the first time in the study period. The following methods were used: diagnostic survey, analysis of medical files and observation. Study data were collected using the survey technique and the following tools: the risk scale for pressure ulcer development by Norton, the Abbreviated Mental Test Score (AMTS), the Activity of Daily Living scale (ADL), the Mini Nutritional Assessment scale (MNA), Torrance's scale, the digital measurement of chronic wound based on color, and the proprietary survey questionnaire. The statistical analysis was carried out using the STATISTICA 13.3 PL suite (StatSoft, PL). Quantitative variables were presented as arithmetic mean, standard deviation, minimum, maximum, median. Qualitative variables were presented as abundances and frequencies. Distribution of quantitative variables was assessed using the Shapiro-Wilk and the Kolmogorov-Smirnov tests, and equality of group variances were assessed using the Levene’s test. The analysis of significance differences was based on the U Mann-Whitney and the Chi-squared (χ2) tests. Kruskal-Wallis test was also applied, as well as appropriate post-hoc tests, the Pearson’s Correlation Coefficient and the Spearman’s Rank Correlation Coefficient. For all analyses, effects with probability value p below the accepted significance level of α = 0.05 (p < 0.05) were considered significant. RESULTS ; . The risk of pressure ulcers was confirmed in 21.1% and presence of pressure ulcers in 9.8% of hospitalized subjects. During the hospital stay, pressure ulcers developed in 56 subjects, including 44 with no pressure ulcers at admission, and 12 suffering from pressure ulcers at the point of admission, who developed an additional wound during their hospitalization. A single subject had 1 to 7 pressure ulcers, graded Torrance I to IV. Pressure ulcers were present in various localizations. Most commonly on the sacral bone. According to the measurement of chronic wounds based on color, pink color dominated in the study group (42.7%), followed by red color (41.3%). Mean dimensions of pressure ulcers were up to 4.7x4.7 cm (SD = 1.7). Tests demonstrated a statistical significance of correlation between presence of pressure ulcers and following risks: terminal condition (p = 0.0121), death (p = 0.0132), oxygen therapy (p = 0.0251), increased potassium level (p = 0.0315), history of smoking (p < 0,00001), extended period of smoking and number of smoked cigarettes (p < 0,00001) and education level (p = 0.0248). A higher incidence of pressure ulcers in the study group was found correlated with presence of: urinary system disease (p = 0.0460), cardiovascular disease (p = 0.0252) and tumors (p = 0.0330), and with the use of steroid therapy (p = 0.0289) and supports, such as pillows (p = 0 ; .0350). The statistical analysis demonstrated correlations between the risk of pressure ulcers and the following factors: fever at admission (p = 0.0179) and during hospitalization (p = 0.0297), thin and paper-like skin (p < 0,00001), urination to diapers (p < 0,00001), troubles with bowel movement control (p < 0,00001), protein level (p < 0,00001), albumin level (p < 0,00001), iron level (p < 0,00001), CRP (p < 0,00001), starvation, emaciation and underweight (acc. to BMI) (p < 0,00001), MNA malnutrition (p < 0,00001), severe malnutrition acc. to the albumin level criterion set by Bruno Szczygiel (p < 0,00001), diabetic and liquid-nutritional diet (p < 0,00001), moderate and severe impairment (acc. to AMTS) (p < 0,00001), moderate impairment (acc. to ADL) (p < 0,00001), diabetes (p = 0.0271), respiratory system disorders (p = 0.0049) and psychoorganic syndrome (p = 0.0048). CONCLUSIONS. Each patient admitted to the hospital being over 65 years of age, with fever, limited mobility, mental impairment, coexisting diseases (of the respiratory system and psychoorganic syndrome), urinary and stool incontinence, should be assessed for the risk of pressure ulcers, and appropriate preventive measures should be introduced. Standard clinical chemistry tests, including albumin, protein, iron, hemoglobin and CRP should be considered in risk patients. Patients with pressure ulcers an ; d coexistent disease of the urinary system, cardiovascular disease and tumors, those with high potassium level and treated with steroids, past and present smokers, and terminal patients should be offered a special care involving preventive measures, monitoring and treatment of pressure ulcers. Pressure ulcers patients should not be offered standard support with regular pillows, as they increase incidence of pressure ulcers. Healthcare systemic measures should be taken in order to improve care of dependent patients staying at homes.