A deficiency of available copper in the soil is reported to have caused a nutritional disease of oats in Europe (1) and in Australia (2), but apparently this disease has not been reported in this country. However, a similar disease has appeared in oats planted on the Experiment Station Farm at Gainesville, Florida, and this report is concerned with the symptoms of the trouble and the remedy for it. The oat variety, Florida 167, when grown on certain parts of the Experiment Station Farm, has exhibited for several years an apparent nutritional disease. Others varieties have been affected, although they have been grown to a lesser extent. The symptoms of this disease develop on this variety as follows: After being seeded at the usual planting time in November, the oats come up and at first appear normal. The only difference detected after about two months is that the affected oats are smaller than nonaffected plants. In later stages of growth, about three degrees of severity of the symptoms have been noted, namely, severe, moderate, and slight. In severe cases the leaves begin to show a characteristic marginal chlorosis early in February. As the disturbance progresses, the margin and tips of the leaves become brown or may look as if they have been scorched. Tillers begin developing about the middle of February. The emerging tips forming the bud of the tillers frequently are rolled up tightly, and the rolled-up part becomes light colored, then brown, and eventually may die. After that the entire plant may die or may struggle along, putting out new tillers which in turn develop similar characteristics. Such plants produce practically no heads and little foliage. If the condition is moderate, the plants will have some of the characteristics described above. New tillers develop late, which results in the plant material being immature at normal harvesting time. The oats produce heads, but instead of ripening to a normal yellow color, these heads tend to have a whitish-green color, and very little grain is produced. Slightly affected plants appear normal except for considerable blasting and light grain. Sometimes the upper leaves, which cover the head just as it emerges, are chlorotic and may even appear scorched. Symptoms of this nature on this variety have been observed on several farms in central Florida. Affected plants seem to develop wiry roots that show root rot in various stages, but this is probably secondary in nature. There was no apparent difference in the amount of Helminthiosporium leaf spot on affected and normal plants. Field experiments, in which the Florida 167 variety was grown, were conducted in a badly affected area' in an effort to determine the cause of the abnormality. In one set of experiments a uniform liberal application of the major fertilizer elements, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur, was applied. In addition to the major elements, copper, zinc, manganese, boron, and molybdenum were applied to the soil in all possible combinations before seeding the oats. The copper was applied as copper chloride at the rate of 10 pounds/acre. The seed were treated with New