In 25 patients with moderate to severe asthma, we compared the therapeutic effectiveness of classic Chinese acupuncture with that of "placebo" acupuncture administered in a randomly ordered, subject- and evaluator-blind, crossover fashion twice weekly for 4 weeks. Real and placebo acupuncture periods were each preceded and followed by 3- to 4-week periods during which no acupuncture was administered. Outcome variables consisted of the following: daily symptoms and medication use self-scored on patient diaries, spirometry and whole body plethysmography performed once weekly during the entire course of the study and repeated serially during 3 hours after real and placebo acupuncture treatment, patients' self-assessment of acute efficacy of acupuncture therapy, and physician's physical findings before and after acupuncture treatment. Two-way analysis of variance failed to reveal a significant effect of either form of acupuncture on symptoms, medication use, or lung function measurements. Similarly, no significant acute effect of acupuncture on lung function, self-ratings of efficacy, or physician's physical findings was found by covariance analysis or the Wilcoxon signed-rank test. When data during the entire course of the study were examined on an individual basis by analysis of variance with repeated measures, only two subjects demonstrated significantly favorable responses to real versus placebo acupuncture, but one subject demonstrated the reverse, suggesting that these responses were not specifically related to acupuncture therapy. Thus, our findings failed to demonstrate any short- or long-term benefit of acupuncture therapy in the management of moderate to severe asthma.