Samples of whole barley cv. Zephyr were cut at 7 stages of growth and after being chopped were ensiled in small laboratory silos. Changes in individual carbohydrates and organic acids during ensilage were studied. The water‐soluble carbohydrates, which rose to a maximum (32.6% of the dry matter) at the milky kernels stage of growth, consisted mainly of fructosans with smaller amounts of fructose, glucose and sucrose. The main organic acid of the plant, malic acid, disappeared during ensilage. The practical significance of the changes is discussed.