the bronchodilator effects were compared in 16 stable asthma patients for 12 hours after either 12 μg formoterol or 200 μg salbutamol from a metered-dose aerosol in a randomized, double-blind, crossover study. The FEV1 measured before 1, 2, 4, 6, 8, 10 and 12 hours after administration was used as the parameter. From 2 hours onwards after dosage, the bronchodilator effect of formoterol was statistically significantly greater than that of salbutamol. The effect of formoterol lasted longer, and even after 12 hours, the FEV1 was still 20 percent above the baseline value. This is clinically significant and offers new possibilities for treatment of the so-called 'morning dip'. Both agents were well tolerated.