The Dynamic Illegible E (DIE) test measures visual acuity with head held still while reading a specially designed visual acuity chart of E's. The head is then moved passively and the change in visual acuity is recorded. The DIE test has previously been shown to be very useful for assessing patients with aminoglycoside ototoxicity. In the present study, statistical analysis using multiple regression showed that the degree of abnormality in the DIE test during horizontal and vertical head movement was correlated with the degree of caloric reduction. Ridit analysis allows comparison between a number of naturally ordered categories. The ridit analysis showed significant differences between groups of patients with varying degrees of caloric reduction. There was also a significant difference in DIE test scores between a group of normals with no history of otoneurological complaint and an age- and sex-matched population of dizzy patients with normal caloric results. As none of our 110 normal patients had more than a one row drop while reading the DIE test with head moving, we feel that it is safe to regard a drop of more than two rows with head moving as abnormal. Perhaps even a mild caloric reduction represents relatively severe vestibular damage and the DIE test has the potential to delineate some patients who have no caloric reduction.