Tables of normal values are available for the measurement of four sagittal diameters (Roof, FM, C1 and C2) and areas of the soft tissue of the nasopharynx as seen in the lateral neck radiograph. The lateral neck radiographs of 100 nasopharyngeal carcinoma (NPC) cases as well as 100 normal controls of corresponding sex and age distribution are measured to ascertain the usefulness of the above measurement in the detection of NPC. Depending on the method of calculation, figures for positive results (sensitivity) may rise to as high as 85% but the specificity (i.e. probability of a correct diagnosis in a person without NPC) is at the same time lowered to 92%. The detection of NPC from any lateral neck radiograph, however, presents a different problem compared to the situation when a person clinically suspected of having NPC is referred for radiography. Many factors are involved in the former situation and it is to this situation that the predictive value (PV) of the scores has to be employed.