PURPOSE: Mucopolysaccharidosis (MPS) is a lysosomal storage disease that causes tissue distortion and dysfunction due to the infiltration of mucopolysaccharide in connective tissue. The purpose of this study was to evaluate the characteristic findings of abdominal CT and plain chest radiography in patients with MPS. MATERIALS AND METHODS: Sixty-two children with MPS diagnosed by urine analysis were involved in this study; 24 of these underwent abdominal CT and the findings were reviewed by two radiologists, who reached a consensus. Organomegaly was classified as severe, moderate or mild. On chest PA radiographs of 42 of the children, the transverse diameter of the trachea was measured and compared with that of 42 normal controls. Student's t test was used for statistical analysis. RESUTLS: At abdominal CT, hepatomegaly was observed in 22 patients (92%; 2 severe, 15 moderate and 5 mild); and splenomegaly was present in 18 (75%; 2 severe, 4 moderate and 12 mild). Among eight patients (33%) with pancreatic enlargement, one had a severly enlarged pancreas, while in the remaining seven, enlargement was mild. Also present were inguinal hernia (n=15), umbilical hernia (n=12), undulation with thickening of the diaphragmatic crura (n=10), abnormalities related to the male genitalia (n=5) and vascular anomaly (n=3). In MPS patients, the mid-point diameter of the trachea (range, 5.6-9 mm; mean, 6.9 mm) was significantly less than in normal controls (range, 8-14 mm; mean, 10.8 mm) (p<0.001). CONCLUSION: An awareness of the characteristic abnormalities observed at abdominal CT and chest PA radiography can lead to a better understanding of MPS in children.