This comparative study was designed to ascertain whether any differences existed between skeletal class Ⅱ malocclusion (<ANB 5°) and skeletal class Ⅲ malocclusion (<ANB -1°) with respect to the craniofacial morphology and nasopharyngeal area. A total of 121 males and 125 females representing different ages were examined. For the purpose of comparison, each malocclusion was classified by sex, and further subdivided into three different age groups; l2-years-of-age-and-under, l3-to-15-years-of-age, l6-years-of-age-and-over. The conclusions were as follows; 1. There were no differences in the area of bony nasopharynx between both types of malocclusion. 2. As a whole, the areas of adenoids of skeletal classⅡ malocclusion tended to be larger than those of skeletal class Ⅲ malocclusion. However, statistically significant differences were found only in the l2-years-of-age-and-under groups of both sex. 3. The areas of nasopharyngeal cavity of skeletal class Ⅲ malocclusion were in general larger than those of skeletal class Ⅱ malocclusion. Statistically significant differences, however, were discovered in the l2-years-of-age-and-under group as well as the l3-to-15-years-of-age group of male. 4. There were significant differences with respect to the rate of area of adenoids to nasopharynx in the l2-years-of-age-and-under groups of both sex and l3-to-15-years-of-age group of male. 5. Cranial base angle showed positive correlation with the depth of nasopharynx and negative correlation with the height of bony nasopharynx. 6. <SNA, <SNB and <ANB were not associated with the size of bony nasopharynx, adenoids and pharyngeal cavity.