Lung volume (LV) in meat-type chickens was measured by water displacement and was computed as a percentage of body weight (BW). The percentage of LV/BW declined from 2.02 +/- 0.190% at day 1 to 1.38 +/- 0.163% at day 144. Pulmonary hypertension caused by insufficient lung capillary capacity or oxygen exchange area results in right ventricular failure and ascites in meat-type chickens. Insufficient LV in very fast-growing broilers may contribute to this problem. Selection procedures in meat-type chickens should include a method for estimating LV.