The marginal capillary plexus of cornea of the hypertensives was studied and the following results were obtained: 1. The width of arterial foot was 3 μ or less for 38.7% and 4-5 μ for 49.7% while it was less than 5 μ for the majority. This width was narrower than that of healthy persons. There was a tendency that the width narrowed with the age and the progress of hypertension. 2. The width of venous foot was 7 μ or less for 19.3% and 8~10 μ for 52.0% while it was less than 10 μ for the majority. This width was also narrower than that of healthy persons. There was a tendency that the width increased with the age and the rise of systolic as well as diastolic blood pressure. 3. As for the width and length of capillary loop and the direction of blood vessels, they were not much different from healthy persons and these things had nothing to do with the age and blood pressure. 4. Hemorrhage was seen though in a very few cases, and it was regarded as an in important clue to diagnosing. 5. The partial dilatations of venous foot were found in 75.0% of them. Those dilatations were fusiform or spindle-shaped, the occurrence of the former increasing with the age and the rise of systolic as well as diastolic blood pressure. It seemed that the factors of hypertension were the cause of the partial dilatations. 6. The occurrence of the intermittence and stasis of blood flow was more frequent than in healthy persons, the former affecting 39.2% and the latter, 8.2% of them. The frequency of occurrence increased with the age and the rise of systolic as well as diastolic blood pressure. 7. The speed of blood flow was slower than normal for 80.7% of them, the abnormality and its ingravescence increasing with the age and the rise of systolic blood pressure. 8. The formation of granules in blood flow was found in 56.7% of them, the percentage of granules being much higher than that of healthy persons. The frequency of occurrence rose with the age and the rise of systolic as well diastolic blood pressure. 9. The abnormality in blood volume was not characteristic in this case. 10. The comparative study of the arteries of the eye ground and the marginal capillary plexus of cornea revealed the existence of a close inter-relationship between them. 11. The effect of the cold weather on them was not much different from that on healthy persons, but it increased the width of venous foot and raised the ocurrence and ingravescence of the fusiform and spindle-shaped dilatation.