Results from one immunotherapy study can be difficult to extrapolate when physicians use products or dose schedules that differ from the ones used in that particular study. The purpose of this study was to determine if an alum absorbed Alpare D. pteronyssinus extract administered in a maintenance dose of 10,000-12,500 BU's could be shown to improve symptoms in asthmatic patients allergic to D. pteronyssinus. Previous studies using higher doses of extracts suggested efficacy but frequent side effects were noted. A double blind placebo controlled study was performed which included 24 active and 25 placebo patients. We measured skin reactivity, methacholine challenge changes, symptoms by visual analog score, specific IgE levels, and end of study assessment. The results showed significantly greater improvement in actively treated patients versus those given placebo in specific IgE levels, symptoms by visual analog score, and end of study status. We saw no significant differences in skin reactivity, methacholine challenge, or diary medication scores. In addition, no difference in side effects was noted between the two groups. We conclude that the dose administered in this study was safe and well tolerated. Some clinical improvement did seem to occur but the study suggests that higher doses may be indicted in certain patients.