Background: Vaccine pharmacovigilance (PV) aims to detect, assess, comprehend, communicaternand manage adverse events following immunization (AEFI). To help distinguish vaccine relatedrnAEFIs from coincidental occurrences, an active PV prospective surveillance programs (e.g. hospitalbasedrnrnsentinel sites) are needed. We describe our experience in assessing system and facilityrnreadiness for implementing a pilot active AEFI PV in Addis Ababa, Ethiopia. rnMethod: Three hospitals were selected for this study after objectively evaluating all the governmentrnhospitals in Addis Ababa using parameters ;ongoing collaborations with the Ethiopian Food andrnDrug Authority (EFDA), previous experience in research, being referral government hospital andrnproximity to key AEFI stakeholders in Addis Ababa. We developed a readiness assessment togetherrnwith scoring tool and system readiness assessment tool by adapting published framework. The siternassessment was conducted via in person interview of specific departments in each hospital while arndesk review of AEFI guideline, Expanded Program for Immunization (EPI) guideline, EFDA andrnEthiopian Public Health Institute (EPHI) website was done for system readiness. rnResults: Three out of thirteen (23.1%) hospitals in Addis Ababa met the criteria for our siternassessment. During the system readiness assessment, we found that essential components were inrnplace, Specific regulation and proclamation on AEFI surveillance except mentioning responsibilityrnof every stakeholder on the guideline was, however absent. Based on the scoring tool, Tikur AnbessarnSpecialized Hospital (TASH) scored 94 out of 155 (60.6%), Saint Paul Hospital Millennium MedicalrnCollege scored 75 out of 155 (48.38%) and Gandi Memorial Hospital scored 62 out of 155 (40%).rnPaper-based records were used by all departments except those of laboratory and radiology in TASHrnand SPHMMC. International Classification of Disease (ICD) 9/10 coding was only used in TASH.rnCopies of national AEFI guidelines were not present in all departments and reporting forms werernfound only in 4 departments surveyed across the three hospitals. Staff at both Gandi MemorialrnHospital and SPHMMC reported absence of training on AEFI surveillance.rnConclusion: TASH has the highest score after assessing readiness for piloting active AEFIrnsurveillance. We also identified the following areas for improvement in all hospitals to ensurernsuccessful implementation: training, making guideline and reporting forms available, and ensuring arnsystem that accommodates paper-based and electronic record systems.