Aim of the present systematic review was to evaluate whether children and adolescents with attention-deficit/hyperactivity disorder (ADHD) are at greater chance of developing bruxism compared to individuals without this disorder. Observational studies that evaluated the occurrence of bruxism in children and adolescents with ADHD were included. The quality of the evidence was evaluated using the Grading of Recommendations, Assessment, Development and Evaluation criteria. Thirty-two studies involving a total of 2629 children/adolescents with ADHD and 1739 with bruxism (1629 with sleep bruxism and 110 with awake bruxism) were included. The prevalence of bruxism, irrespective of type, in the children/adolescents was 31% (95% CI: 0.22-0.41, I = 93%). ADHD was associated with an increased chance of bruxism (OR: 2.94, 95% CI: 2.12-4.07, I = 61%), independently of the type [sleep bruxism (OR: 2.77, 95% CI: 1.90-4.03, I = 66%) or awake bruxism (OR: 10.64, 95% CI: 2.41-47.03, I = 65%)]. The presence of signs of ADHD without a diagnostic confirmation was not associated with an increased chance of bruxism (OR: 3.26, 95% CI: 0.76-14.04, I = 61%). Children and adolescents with a definitive diagnosis of ADHD are at greater chance of developing sleep and awake bruxism than those without this disorder.Copyright © 2020 Elsevier Ltd. All rights reserved.