When hospitalized, patients may undergo procedures for surgery, treatments (eg, blood transfusions), or for diagnostic purposes (eg, biopsy). The principal procedure is the procedure performed for definitive treatment. Hospitalizations usually involve multiple procedures, which together constitute the all-listed procedures performed during a hospital stay. Data on inpatient hospital procedures can help hospital administrators, health practitioners, researchers, and others understand how hospital care, including care related to diagnosis and treatment, is currently provided and what changes or consistencies in care delivery have occurred over time. The present Statistical Brief presents 2011 data on the most common all-listed procedures performed during hospital stays in the United States, overall and by patient age. Changes between 1997 and 2011 in the number of stays and in the rate of hospitalizations with these procedures are also presented. All differences between estimates noted in the text are statistically significant at the. 001 level or better.