Background: Polysomnography (PSG) is the gold standard for sleep bruxism (SB) diagnosis. PSG/SB children's criteria are not available; thus, parental-report SB is widely used. Aim: Assessing the diagnostic accuracy of parental report of sleep tooth grinding (STG) with a PSG/SB diagnosis in children, adopting adult criteria. Design: Thirty-seven children from clinics of Universidad CES were included. Parents filled the Children's Sleep Habits Questionnaire (CSHQ) assessing the single-observation report – CSHQ – of STG with a No/Yes answer and five ordinal answers. A 5-day diary reporting the presence/absence of STG (multiple-observation report) was also completed. Each child underwent a single-night PSG study. Sensitivity, specificity, positive predictive value, negative predictive value, accuracy, likelihood ratios, Spearman correlation coefficient, and Cohen's kappa coefficient were used to analyze data. Results: Single observation, using No/Yes answer, showed acceptable specificity and NPV, while low PPV and sensitivity. Accuracy and likelihood ratios were low. When using the five ordinal answers, weak correlation and fair agreement (r = 0.34 and κ = 0.40) with PSG/SB adult criteria were found. Multiple-observation evaluation of STG presented moderate correlation and agreement (r = 0.50 and κ = 0.48). Conclusions: Although multiple-observation report achieved better agreement than single-observation report, our results failed supporting the validity of report strategies for the diagnosis of SB in children, as an equivalent of PSG/SB adult criteria.