objectives: to verify pressure ulcer prevalence in hospital units of adult patients in the university hospital of the university of s？o paulo (hu-usp), and to verify interrater reliability in risk assessment, using the braden scale. methods: a quantitative, exploratory study. data were collected by six trained collaborators who conducted physical exams and risk assessment in 87 patients, an evaluation that is considered the "gold standard". data from the assessments performed by the nurses, of those same patients, were collected from the patient records. results: we verified the pressure ulcer prevalence within the hospital was 19.5%, with 63.6% prevalence in the intensive care unit, 15.6% in the surgical clinic, 13.9% in the medical clinic, and 0% in the semi-intensive [step-down] unit. regarding interrater reliability in the clinical evaluation of the patients, there was strong agreement in the subscores of: sensory perception, activity, mobility, friction/shear. moisture and nutrition showed lower agreement, suggesting that these subscores require discussion to verify the causes of the discrepancies. conclusion: pressure ulcer prevalence studies provide the possibility to verify the extent of the problem and provide input for the construction of strategies and prevention programs.