10 patients with reversible bronchospasm received by the oral route in a double-blind fashion broxaterol, Z. 1170, 0.250 and 0.500 mg in comparison with salbutamol 4 mg as base and a placebo. Measurements of FEV1, heart rate and arterial pressure were performed before and 0.5, 1, 2, 4, 6 h after each treatment. Z. 1170 was followed by increases in FEV1 over the baseline and the placebo values that were significant up to the 4th hour with the 0.500 mg dose, up to the 2nd hour with the 0.250 mg dose. The difference between the effects of the two dose levels of Z. 1170 was significant, and the effect of the 0.500 mg dose was not significantly different from that of salbutamol 4 mg. The maximum increments in FEV1 following Z. 1170 averaged 15.8% for the 0.250 mg dose, 24.3% for 0.500 mg dose, and they were recorded at the 2nd hour. At this time point the mean increment in FEV1 following salbutamol was 18.0%. The maximum increments in FEV1 with salbutamol averaged 18.7% and were recorded at the 1st hour. At this time the mean increments for Z. 1170 0.250 and 0.500 mg were 13.8 and 20.0%, respectively. Heart rate and arterial pressure did not show any changes of clinical significance.