Two trials using a total of 1,484 Ross male broilers were conducted to study the effect of air velocities of 180 and 120 m/min versus still air (<15 m/min) on BW gain (BWG) and feed:gain from 3 to 7 wk of age. Broilers were raised in a common environment to 3 wk of age. The experimental facility was a closed sided house containing eight wind tunnel floor pens and six floor pens. There were two wind tunnels (four pens/tunnel) used to test air velocities of 180 or 120 m/min. At 3 wk of age, 53 birds were placed in pens on litter in each of two wind tunnels (four pens/tunnel) or on litter in floor pens (six pens) in an environmentally controlled facility. All floor pens contained 3.75 square meters of floor space, one tube feeder, and one trough waterer. The temperature regimen was a diurnal cycle of 25-30-25 C with 23 C dewpoint. Air velocities of 180 and 120 m/min had no significant effect on BWG or feed:gain during the first week (3 to 4 wk) in the tunnels as compared with the still air. However, significant improvements were noted in BWG and feed:gains for increased air velocities from 4 to 5 and 5 to 6 wk of age. During the last week (6 to 7), an air velocity of 180 m/min significantly improved BWG and feed:gain, as compared with the 120 m/min or the still air.