The breathing pattern was studied in man during inspiratory elastic load applied throughout the breathing cycle (CL) or inspiration only (DL). $V_{T}$ decreased similarly under both loads — 40% during the 1st loaded breath (1st), 25% after 1 min (min) — as did Ti (15% at 1st, 25% at min); Te decreased by 35% under CL, 25% under DL, at both times. Under DL expiratory flow started after a lag of 0.4 sec, required to raise alveolar pressure above atmospheric pressure. In all subjects the inspiratory drive was increased at 1st and in 6 out of 8 the ventilatory response at min was essentially neurogenic. The rate of decrease of inspiratory muscle pressure during the period of zero flow under DL was proportional to end-inspiratory muscle pressure (Pmus{e.i.}) and to Pmus{e.i.}/Ti. At the beginning of expiration dPmus/dt was greater under DL: in this period the difference of Pmus between CL and DL seems mainly due to intrinsic muscle properties.