Objective The aim of this study was to investigate the developmental relationship between adenoid tissue volume and mastoid air cell volume, using a 3D reconstruction technique. Study design Cross-sectional retrospective study. Subjects and methods Multislice computed tomography (MSCT) images were obtained using three-dimensional (3D) reconstruction and volume-rendering techniques (VRT). The subjects were 63 boys and 37 girls, 3–16 years of age. The volumes of bilateral mastoid air cells and adenoids marked in axial–coronal–sagittal planes were calculated. The patients were grouped into three categories according to adenoid tissue volume, total mastoid volume (TMV), and age. Results No significant difference was noted between the right mastoid volume (RMV) and the left mastoid volume (LMV) or between age and sex ( p = 0.368; p = 0.549; p = 0.454). The incremental increase in adenoid tissue volume did not correlate with TMV ( r = −0.161, r = −0.279, r = 0.015). The incremental increase in TMV did not correlate with the volume of adenoid tissue ( r = 0.024, r = 0.148, r = 0.017). Conclusions No significant correlation was obtained between the incremental increase in adenoid tissue volume and TMV or the incremental increase in TMV and adenoid tissue volume. There does not seem to be a developmental relationship between adenoid tissue volume and TMV.