OBJECTIVE: This study aimed to evaluate the occurrence of coronavirus disease 2019 (COVID-19) in hemodialysis facilities and the occurrence of and risk factors for clustering of COVID-19 cases. METHODS: We conducted a cross-sectional online survey between March and July 2020, in all dialysis facilities in São Paulo state, using Google Forms. The online questionnaire contained questions addressing specific components of infection prevention and control practices and the number of cases during the COVID-19 pandemic. RESULTS: A total of 1,093 (5%) COVID-19 cases were reported among 20,984 patients; approximately 56% of the facilities had ≥1 cluster. Most facilities implemented various measures (such as allocation of dedicated COVID-19 areas/shifts, symptom screening, environmental disinfection, and maintenance of adequate ventilation) to prevent the transmission of severe acute respiratory syndrome coronavirus 2. Clustering of COVID-19 cases was suspected in only 7% of dialysis facilities. The only variable associated with this event was the performance of aerosol-generating procedures (odds ratio: 4.74; 95% confidence interval: 1.75-12.86). CONCLUSION: Attention should be paid to avoiding the performance of aerosol-generating procedures in dialysis facilities and monitoring the clustering of cases.