Background/Aim: The optimal mouthguard type and design for each player and sport are currently unknown. The aim of this study was to assess the effect of using a thicker custom-made mouthguard with occlusal accommodation on the degree of satisfaction among water polo players. Material and Methods: Twenty-five elite water polo players participated in this randomized four-period crossover trial conducted from February to May 2019. For each participant, two customized mouthguards were fabricated using 4-mm ethyl vinyl acetate foil: Type A included no occlusal accommodation, and Type B included a 2-mm occlusal accommodation. Players wore each mouthguard during training sessions and competitions for 2 weeks in one of two randomized sequences. After each match or training session, players were asked to evaluate the mouthguards on 10-point scales across three domains: discomfort or interference with function, protection, and general satisfaction. Mouthguard preference was also recorded. Results: The mouthguard with occlusal accommodation was reported to interfere more with speech and swallowing (P < .001) and with esthetics, breathing, and athletic performance (P < .05) compared with the conventional mouthguard. Although occlusal accommodation was associated with a higher perceived degree of protection (mean difference 0.5; 95% CI: 0.2-0.8), players were still more satisfied with the conventional mouthguard (mean difference 1.5; 95% CI: 0.8-2.3). Two players preferred the occlusal mouthguard, whereas 22 preferred the conventional mouthguard (P = .007). Conclusions: Among water polo players, occlusal accommodation increasing the thickness of the custom-made mouthguards may offer a greater perceived sense of protection, but this comes at the cost of greater discomfort and reduced overall satisfaction. Dentists can recommend conventional mouthguards for most water polo players.