In a randomized, double-blind, parallel-group trial, 47 children with acute asthma received a combination of ipratropium bromide solution (250 micrograms) and fenoterol hydrobromide solution (625 micrograms), fenoterol solution (625 micrograms) alone, or ipratropium solution (250 micrograms) alone, administered by face mask and nebulizer, with the dose repeated 60 minutes later. The groups did not differ significantly with regard to age, pulmonary function at baseline, or any other variable. They were monitored at 30, 60, 90, and 120 minutes by use of a clinical score, oxygen saturation, and pulmonary function tests. At the end of the study, albuterol was administered to assess residual bronchoconstriction. Clinical scores improved significantly after treatment in all groups at all times compared with baseline. The greatest improvement in FEV1 was seen in the patients treated with ipratropium/fenoterol, whether considered as absolute change, change in percent predicted, or percent change from baseline. Ipratropium/fenoterol was significantly better than fenoterol alone only when considered as percent change from baseline. Improvement in flow at mid and low lung volumes was significantly greater for the ipratropium/fenoterol combination than for ipratropium alone; no significant differences were noted between ipratropium/fenoterol and fenoterol for flow at mid and low lung volumes. Treatment with albuterol did not significantly improve pulmonary function in the groups receiving ipratropium/fenoterol or fenoterol alone, but it did increase flow at all lung volumes in the group receiving ipratropium alone. No patient complained spontaneously of any adverse reactions, and no clinically significant changes in heart rate or systolic or diastolic blood pressures occurred.(ABSTRACT TRUNCATED AT 250 WORDS)