This study examines the reliability of parental concern (PC) as an indicator for mental disorders in preschool-aged children in a clinical setting, aiming to establish sensitivity and specificity, evaluate PC's predictive value for specific diagnoses, and explore the influence of child age on predictions. The sample comprises 574 children referred to child psychiatry services (mean age 47 months, 73% boys). Analyses of sensitivity and specificity for five distinct PC were conducted, while logistic regressions explored the predictive value of PC for corresponding diagnoses, accounting for child age. Language-related concerns emerged as the most frequent and accurate. Sensitivity ranged from 7% to 72%, while specificity ranged from 57% to 97%. PC demonstrated predictive validity for their corresponding diagnoses, except for motor disorders. Child age did not substantially influence these predictions. Findings suggest that systematically incorporating PC into the assessment process for preschool-aged children consulting in child psychiatry is warranted.