This study aimed to evaluate the quality of nursing care of an Adult Intensive Care Unit. Data from fifty in-hospital patients, who stayed in ICU for more than three days, were collected through observation, physical examination and patients' medical-information records analysis, using an Operational Auditing Plan. Care considered of quality were those that obtained positive answer percentage ≥ 70%, as those related to Physical Safety (71%) and Equipment Use (72%). Physical Activity (28%) and Oxygenation/Ventilation (29%) reached the lowest scores. We concluded that is urgent to implement continuing education actions in the service studied, since most care items and sub-items did not present the quality needed.