Ten cadaveric sagittally sectioned head regions as we as thirty coronal CT scans were examined to detect different anatomical variations of middle meatus structures. The results obtained showed that the anatomical variations may affect middle concha, bulla ethmoidalis, uncinate process, hiatus semilunaris, ethmoid cells, maxillary sinus ostium and frontal sinus drainage as regards their shape, size, site, pneumatization, attachments, or drainage way. Some of the detected anatomical variations showed a high incidence of associated sinusitis, whether this association is caused by the anatomical variation itself or other resulting factors such as mucosal contact still needs further studies