It has widely known for speech problem in patients with malocclusion, but there have been insufficient studies on degrees of severity. Patients with openbite and Cl III malocclusion usually have speech problem. It has widely known that fricative /s/is pronunciated most abnormally in Cl III malocclusion than any other consonant. Therefore 20 children with anterior crossbite were selected for study groups and 40 children with normal anterior occlusion were selected for control group. 7 sounds such as / 사(sa), 서($s{delta}$), 소(so), 수(su), 스($s{omega}$), 시(si), 세(se) / were recorded, and the formants and formants ratios were measured by using Sensimetric Speech Station, which is speech analyzing program in IBM PC. The results were as follows : 1. In anterior crossbite group, F1 of all 7 sounds were significantly higher than normal anterior relationship group(p<0.05). 2. There were no significant difference in F2 between two groups except / 소(so), 수(su)/(p>0.05). 3. In anterior crossbite group, F2/F1 ratio of all 7 sounds were significantly smaller than normal anterior relationship group(p<0.05). 4. There were no significant difference in accordance with tongue position(p>0.05).