An information system is analyzed on defining quality indicators for pressure ulcer which is recommended by the American Nursing Association. Objective: Analyzing statistically a large sized hospital electronic database of São Paulo City. Methods: Descriptive retrospective study, sample frame of convenience of 51,414 hospital discharges. Results: Predominance of female sex 60%; average age 52 years old and length of stay of 4 days. Pressure ulcer occurred in 1% of the sample frame. The statistical analysis pointed out the age hospitalization time as significant for the appearing of pressure ulcer. The chance rate of occurrence is 10 times higher for patients aged ≥65 years old compared to the ones of <65 years old (p<0.001). When permanence is over 4 days the chance is 18 times higher of developing pressure ulcer compared to patients whose permanence was up to 3 days (p<0.001). Final considerations: This study proved the worth of an electronic database about clinical practice in planning and managing nursing assistance; validating the indicator and consequently improving quality.