During childhood, perioral muscle function is closely associated with malocclusion. To clarify the effects of tongue function on maxillofacial morphology in children, tongue pressure and maximum lip-closing force (LCF) were measured and the relationship between perioral muscle function and maxillofacial morphology was evaluated according to the skeletal classification. Maximum tongue pressure (MTP) and swallowing tongue pressure (STP) were measured on the anterior palatine rugae in 100 children (Hellman's dental stages IIIA-IIIC) using a balloon-type tongue pressure measurement device. Lip-closing force was measured using an LCF measurement device. Lateral cephalograms were examined to classify subjects into skeletal (S)-I, S-II and S-III groups. Correlations of skeletal classification with tongue pressure and LCF were examined. Correlations of lateral cephalometric measurements with palatal volume (PV), measured using a three-dimensional optical scanner, were evaluated. Maximum tongue pressure was significantly lower in the S-II group than in other groups. Swallowing tongue pressure was significantly lower in the S-II group than in the S-III group. Lip-closing force was significantly higher in the S-III group than in other groups. Swallowing tongue pressure was positively correlated with MTP and PV. Correlations between tongue pressure and anteroposterior skeletal classification indicated the importance of quantitative tongue function assessment.