To describe the scale and scope of inpatient electronic health record (EHR) maintenance following initial implementation. A retrospective study reviewing EHR change documentation within an integrated healthcare delivery system that has 21 hospitals. Between 2010 and 2015, we identified and categorized all significant changes made to the inpatient EHR, as documented within monthly EHR communication updates. We categorized EHR changes as updates to existing functionality or upgrades to new functionality. We grouped changes within larger functional domains as orders, alerts and customization, surgical and emergency department (ED), data review, reports and health information management, and other. We also identified the clinical areas and user roles targeted by these changes. Over a 6-year period, 5551 unique changes were made to the inpatient EHR, with a median of 72 changes per month. Changes most frequently targeted orders (44.7% of 2190 change documents) and order sets (29.9% of documents). In total, changes affected 135 EHR functions. A total of 151 unique user roles were affected by these changes, with the most frequent roles including nurses (30.6%), physicians (26.6%), and other clinical staff (22.7%). The clinical areas most targeted by changes included surgical areas and the ED. Over 6 years, EHR maintenance for clinical functionality was substantial and varied with pervasive impacts, requiring persistent attention, diverse expertise, and interdisciplinary collaboration.