BackgroundAdverse events (AE) resulting from voluntary medical male circumcision (VMMC) are commonly used to measure program quality. Mozambique’s VMMC program data reports a combined moderate and severe AE rate of 0.2% through passive surveillance. With active surveillance, similar programs report AE rates ranging from 1.0 to 17.0%. The objective of this activity was to assess potential underreporting of AEs via the passive surveillance system in Mozambique.MethodsThis mixed-methods assessment randomly selected one third (16) of all 46 VMMC clinics through stratified sampling, based on volume. A retrospective record review was conducted including patient clinical files, stock records of Amoxicillin/Clavulanic Acid (the choice antibiotic for VMMC-related infections), and clinic-level AE rates from the national database. Records from the month of April 21 to May 20, 2017 were analyzed to identify both reported and potentially unreported AEs. In addition, external, expert clinicians observed post-operative visits (n = 167). Descriptive statistics were calculated, including difference between reported and identified AEs, an adjusted retrospective AE rate, and an observed prospective AE rate in each clinic.ResultsA total of 5352 circumcisions were performed in the 16 clinics: 8 (0.15%) AEs were reported. Retrospective clinical record reviews identified 36 AEs (0.67%); AE severity or type was unknown. Using Amoxicillin/Clavulanic Acid dispensation as a proxy for VMMC-related infections, 39 additional AEs infections were identified, resulting in an adjusted AE rate of 1.4%, an 8.3 fold increase from the reported AE rate. Prospective, post-operative visit observations of 167 clients found 10 AEs (5.9%); infection was common and boys 10–14 years old represented 80% of AE clients.ConclusionsEvidence suggests underreporting of AEs in the Mozambican VMMC program. Quality improvement efforts should be implemented in all VMMC sites to improve AE identification, documentation and prevention efforts.