Background: Endophthalmitis is one of the most important adverse events after cataract surgery as it can lead to total vision loss. The aim of this study was to describe the occurrence of endophthalmitis after phacoemulsification with intraocular lens implantation among patients assisted during a joint effort in Porto Velho, Rondonia, Brazil. Method: This is a retrospective cohort study, carried out from a bank with 649 medical records of patients who underwent surgery. Descriptive analysis and multiple analysis using Robust Poisson Regression were performed to estimate relative risks (RR) and 95% confidence intervals (95%CI). A statistical analysis was performed using the statistical program Stata version 16.0 (College Station, Texas, USA). Results: The incidence of postoperative endophthalmitis confirmed by culture was 10.88%, the highest ever recorded in the world. A higher risk for endophthalmitis was found, in probable cases, among males (RR: 1.88; 95%CI:1.03; 3.44) and brown and yellow skin color (RR: 2.78; 95 %CI %: 1.17; 6.60). For confirmed and probable cases, bilateral surgery and specific lens model were also risk factors. The predominant etiological agents were gram-negative and the main clinical manifestation was corneal edema. The average number of days to start treatment was eight days and 27.12% used antibiotics. Conclusion: Specific protocols are needed for cataract surgeries that encompass hiring, performing and monitoring these services to ensure good practices and patient safety.