This Healthcare Cost and Utilization Project (HCUP) Statistical Brief presents statistics on 38 comorbidities, defined by the Elixhauser Comorbidity Software Refined for the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM), v2023.1. Using weighted estimates of adult inpatient stays based on the 2019 National Inpatient Sample (NIS), the percentage of stays with any and specific types of comorbidities is shown. The percentage of stays with comorbidities is examined by patient characteristics and the reason for the hospital stay, and outcomes of inpatient stays with and without comorbidities are presented. Because of the large sample size of the NIS data, small differences can be statistically significant but not clinically important. Thus, only differences greater than or equal to 10 percent are discussed in the text.