The aim of this study was to identify possible nursing diagnoses in patients classified as priority level I and II according to the Manchester protocol. This descriptive retrospective study evaluated 40 medical charts classified as priority level I and II. To identify nursing diagnoses, two experts analyzed signs and symptoms registered in medical charts at the time of risk classification. For priority level I patients, the most frequent nursing diagnoses were acute pain (65.0%), respiratory insufficiency (45.0%), and impaired gas exchange (40.0%). For the priority level II patients, the most frequent nursing diagnoses were acute pain (80.0%), nausea (10.0%), and risk for electrolyte imbalance (10.0%). This study suggests that the use of the Manchester protocol enabled identification of defining characteristics and risk factors and supports the elaboration of nursing diagnoses in risk classification.