Subjecting barley at four stages of development to short-term periods of 2–7 days flooding of a Gleizolic soil reduced the dry weight of the plants from that of non-flooded plants in proportion to the duration of flooding. Barley 14 days old at flooding was injured more than barley 35 days old at flooding, although the injury was more permanent with the older plants. Delayed head emergence and up to 55% reduction in grain yields were measured. Eh values of 289 mv, or less, were measured below the 5-cm depth although there was no flooding-induced increase in the concentration of water-soluble or exchangeable Mn in the soil. The concentration of Mn in the barley was not altered by flooding. Short-term flooding reduced the concentration of N, P and K in the barley. The greatest decrease was measured in the youngest plants; at the end of 7 days' flooding the concentration of N, P and K was reduced by 51, 60 and 58%, respectively. Two wk after drainage, N, P and K levels in the youngest plants recovered to levels equal to non-flooded barley, whereas more mature plants were subject to continued depressed levels. Under the conditions of this experiment, the reduced growth and yield of barley resulting from short-term flooding was not due to Mn toxicity, but may be due to reduced ion uptake resulting from O2 deficiency brought about by the reducing conditions in the soil or other unknown factors.