HCUPnet is an on-line query system that provides free, instant access to the largest set of all-payer health care databases that are publicly available. Using HCUPnet's easy step-by-step query system, you can generate tables and graphs on statistics and trends for acute care hospitals in the U.S. HCUPnet provides:  National and regional estimates for inpatient stays and emergency department visits;  State counts of inpatient stays and emergency department visits for those states that agreed to participate;  National estimates on readmissions and readmission rates;  County-level statistics on hospital use and potentially preventable admissions, based on the AHRQ Quality Indicators (QIs)* For most queries, detailed information is available for conditions and procedures (by ICD-9-CM codes and Clinical Classification Software), and for diagnosis related groups (DRGs). HCUPnet allows easy access to information from datasets that are part of the Healthcare Cost and Utilization Project (HCUP); details on obtaining these datasets are also available in www.healthdata.gov