Several clinical and radiological studies of the proximal sesamoid bones were done in eleven horses from the age of one month to three years. The X-ray findings were found to be inconstant. The number of nutrient canals visualized increased or decreased, and the bone structure gradually became more irregular. Bone deposits along the borders of the sesamoid bones usually did not become apparent until the second or third year of life. Particularly this growth of new bone was found to be a significant clinical feature. On the other hand, nutrient canals and irregular bone structures were also observed in horses in which clinical examination failed to reveal any changes.