OBJECTIVES: To review worldwide data on cochlear implant adverse events, test for significant trends over a 10-year period and discuss possible reasons behind such trends. To evaluate the suitability of the Manufacturer and User Facility Device Experience (MAUDE) database for analysis of trends in cochlear implant adverse events. STUDY DESIGN: Retrospective analysis of cochlear implant adverse events reported to the U.S. Food and Drug Administration (FDA) as recorded on the MAUDE database. Data for each adverse event reported in the years 2000 (n = 237), 2005 (n = 1089), and 2010 (n = 2543) were evaluated and assigned to one of 14 categories according to report content. Incidence data were compared across the 3 sampling points to determine trends. HYPOTHESIS: Improvements in cochlear implant manufacturing processes and surgical techniques would result in a decrease in the proportion of CI adverse events because of primary device failure or surgical factors, relative to those with complex, multi-factorial or idiopathic origins, over the 10 year sampling period. RESULTS AND CONCLUSION: Statistical analyses showed a significant increase over time in the proportion of CI adverse events that had multiple or unknown causes, particularly cases of gradual idiopathic loss of performance, as compared with those with a clearly defined underlying device-related or medical cause. CONCLUSIONS: Findings suggest that there is an urgent need to undertake further research to investigate causes for idiopathic and gradual CI adverse events to continue the overall improvement in CI outcomes.