PURPOSE: The objective of this research is to provide the indoor environment management education program for the asthma patients and their families and then analyze the effectiveness in education preventing allergic asthma. METHODS: A pre-post single group quasi-experimental design was used to provide an education program about correct indoor environment management to a total of 58 households (29 patient households and 29 normal households). The performance rate of correct indoor environment management procedure, amount of house dust mite antigen, allergy subjective symptoms score and knowledge score about indoor environment management were compared before and after the education to test the effectiveness of the education. RESULTS: Home-visit education in this research had effects in improving subject households' performance rate of indoor environment management procedures, reducing the amount of house dust mite antigen - an important inducing factor of allergy, and reducing perceived subjective symptoms of allergy.