We have studied the efficacy and acceptability of a new inhalation spacer device. The functional principle of the device, differing from that of conventional spacers, is based on evaporation of the propellant during circular movement of the aerosol in a small spherical chamber. We assessed the bronchodilating effect of salbutamol (Salbuvent) inhaled with the new spacer (Rondo) compared with salbutamol (Ventoline) inhaled with the spacer Volumatic and with salbutamol (Salbuvent) inhaled with a conventional metered dose actuator using a double-blind cross-over arrangement. Fifteen asthmatic patients were treated over a period of 4 weeks. They used each of the three different devices for 2-3 days every week. Peak expiratory flow rates were recorded every morning after one and after two puffs of the study drugs. The bronchodilator responses to the three treatments were similar within narrow ranges of estimate. By visual analogue scale assessment the new spacer was significantly easier to handle (P < 0.05) and more convenient to carry around (P < 0.01) than Volumatic.