Abstract: PURPOSE To measure the height of the maxillary first molar alveolar crest in different age groups. METHODS A total of 288 patients were divided into 3 groups: young age group (18-34 years), middle age group (35-59 years) and old age group (above 60 years). They were selected to be scanned by cone-beam computed tomography (CBCT), and the height of the first maxillary molar alveolar crest was measured though Kavo eXam Vision software. The data was analyzed with SPSS16.0 software package for Student’s t test. RESULTS In young age group, the height of the maxillary first molar alveolar crest was (9.08±3.70) mm; middle age group, the height was (10.66±3.99) mm; and in old age group, the height was (12.40±4.54) mm. There was no significant difference between males and females in each group, but there were significant differences between different age group in the height of the maxillary first molar alveolar crest.CONCLUSIONS The height of the maxillary first molar alveolar crest is increasing with the increase of age, but there is no difference between males and females. For patients undergoing implantation in maxillary posterior region, CBCT should be performed to determine the height of alveolar crest and anatomy of the maxillary sinus, especially for young patients.