A prospective study was performed about the correlation in the diagnosis of sinus disorders between the PNS X-ray and A-mode ultrasonography. In this study 524 maxillary sinuses were examined out of 323 patients who had signs and symptoms of sinus disorders. The patients were examined with A-mode ultrasonography followed by PNS X-ray. The results were compared with one of the operative findings, character of puncture and irrigation, computerized axial tomography, and biopsy as a method of reference. The results were as follows : 1) Among the 323 patients, 117 were females and 206 were males. The age range was 1 year to 81 years with a median age of 22 years. 2) Seventy four or 14% out of 524 sinuses showed normal findings, 159 or 30.3% showed fluid retention, 29 or 5.5% showed cysts, 236 or 45.1% showed mucosal hypertrophy, 26 or 5.0% showed masses such as malignant tumors or fungal infections. 3) A-mode ultrasonography appeared less sensitive(sensitivity : 84.9%) than PNS X-ray(sensitivity : 89.6%)(p<0.05). 4) The specificity of A-mode ultrasonography was 78.4% while PNS X-ray score 74.3%(p>0.05). 5) The diagnostic accuracy of A-mode ultrasonography was 68.7% while PNS X-ray score 65.1%(p>0.05). A-mode ultrasonography provides information with regard to the maxillary sinus but doesn't in case of the other sinuses such as sphenoid sinus or ethmoid sinus. A-mode ultrasonography can neither detect mild mucosal changes, nor be used to design proper operative technique, nor provide direct information about bone lesion. Ultrasonography may not replace PNS X-ray, but in selective cases ultrasonography may complement PNS X-ray, particularly in the investigation and follow-up of the effect of treatment of possible intrasinus secretions.