In order to assess the efficacy and safety of subcutaneous terbutaline 0.25 mg and 0.5 mg as compared to subcutaneous epinephrine, 28 stable asthmatics were studied. After control of environmental exposures in the clinical research facility at the University Hospitals of Case Western Reserve Medical School, the patients were entered into a double-blind crossover placebo-controlled 4-day study. All of the patients showed significant responses to both doses of terbutaline and after epinephrine as compared to placebo (greater than 15% increase in FEV1). In general, the side effects experienced were similar for 0.25 mg epinephrine and 0.25 mg terbutaline. They were slightly more pronounced with 0.5 mg of terbutaline. In terms of duration of action, there was a substantial difference between the duration of effect of subcutaneous epinephrine and subcutaneous terbutaline at both dosages. No cardiovascular side effects of any significance were noted in this study with either agent. We conclude that subcutaneous terbutaline is at least as effective as epinephrine in the management of reversible bronchospasm and may be considered a drug of choice in stable asthmatics.