RATIONALE: Interventions that target a wide variety of asthma triggers through home visits may be beneficial in improving asthma outcomes. CDC scientists and the Task Force on Community Preventive Services systematically reviewed the evidence of effectiveness of home-based multi-trigger multi-component environmental interventions in improving asthma-related morbidity. METHODS: We sought English language studies that evaluated interventions with at least one home visit, included more than one intervention component, were directed towards reducing multiple environmental asthma triggers, and met the minimum research quality for study design and execution. RESULTS: Twenty-five studies met inclusion criteria. In the 21 studies targeting children, asthma symptom days were reduced by 0.8 days/2weeks (Interquartile Interval or IQI: -0.9 to -0.6 days/2 weeks) equivalent to 21 symptom days/year, school days missed due to asthma were reduced by 11 days per year (IQI: -18.2 to -2.9 days), and the number of asthma acute care visits were modestly reduced by 0.57 visits per year (IQI -1.7 to -0.3). Only four studies reported outcomes among adults with asthma and found inconsistent results. CONCLUSIONS: Findings from this review indicate that home-based multi-trigger, multi-component, environmental interventions are effective in reducing symptom days, school days missed, and acute asthma visits in children with asthma. We cannot draw any conclusions on the effectiveness of this intervention in adults due to the small number of studies with inconsistent results. Additional studies are needed to evaluate 1) the effectiveness of this intervention in adults; 2) evaluate cost-effectiveness; and 3) determine the individual contributions of the various intervention components.