© 2021 American Academy of PeriodontologyBackground: Peri-implantitis (PI) is a growing concern in the dental community worldwide. The study aimed to compare U.S. versus European periodontists’ considerations of risk factors, diagnostic criteria, and management of PI. Methods: A total of 393 periodontists from the United States and 100 periodontists from Europe (Germany, Greece, Netherlands) responded to anonymous surveys electronically or by mail. Results: Compared to U.S. periodontists, European respondents were younger, more likely to be female and placed fewer implants per month (9.12 vs 13.90; P = 0.003). Poor oral hygiene, history of periodontitis, and smoking were considered as very important risk factors by both groups (rated > 4 on 5-point scale). European periodontists rated poor oral hygiene (4.64 vs 4.45; P = 0.005) and history of periodontitis (4.36 vs 4.10; P = 0.006) as more important and implant surface (2.91 vs 3.18; P = 0.023), occlusion (2.80 vs 3.75; P < 0.001) and presence of keratinized tissue (3.27 vs 3.77; P < 0.001) as less important than did U.S. periodontists. Both groups rated clinical probing, radiographic bone loss, and presence of bleeding and suppuration as rather important diagnostic criteria. They rated implant exposure/mucosal recession as relatively less important with U.S. periodontists giving higher importance ratings than European periodontists (3.99 vs 3.54; P = 0.001). Both groups nearly always used patient education, plaque control and mechanical debridement when treating PI. U.S. periodontists were more likely to use antibiotics (3.88 vs 3.07; P < 0.001), lasers (2.11 vs 1.68; P = 0.005), allograft (3.39 vs 2.14; P < 0.001) and regenerative approaches (3.57 vs 2.56; P < 0.001), but less likely to use resective surgery (3.09 vs 3.53; P < 0.001) than European periodontists. Conclusions: U.S. and European periodontists’ considerations concerning risk factors, diagnosis and management of PI were evidence-based. Identified differences between the two groups can inform future educational efforts.