In a cross-sectional study, the prevalence rates of overall and specific mental health problems (MHP), as well as consequential impairments, were examined in a representative community sample of German preschoolers. MHP in 391 children were assessed by applying the Strength and Difficulties Questionnaire, as well as its impact supplement. Furthermore, the child behaviour checklist 1(1/2)-5 (CBCL 1(1/2)-5) and the IOWA-Conners behaviour rating scale were applied. Prevalence rates of MHP with 95 % confidence intervals (95 % CI) were determined. Odds ratios were calculated to analyse the relationships between MHP, age, gender, socioeconomic status, and geographical region using logistic regression. Overall, 7.4 % of the children showed symptoms of MHP. 12.9 % of the children were considered to be impaired by psychosocial problems. Depressive and anxiety symptoms were present in 4.2 % of the children; 11.8 % showed hyperactivity symptoms. The observed prevalence rates call for early mental health prevention in preschoolers.