In bronchial asthma, house dust is one of the important precipitating factor. Cimex lectularius or bedbug is a well known house insect and share in the constitution of house dust. 54 asthmatic patients and 11 control individuals were skin tested using the common environmental inhalant antigens as well as Cimex extracts (Head and thorax, 1st antigen and abdomen, 2nd antigen). Also precipitin test using both Cimex extracts were used. The percentage of positive skin reactions to 1st Cimex antigen was 37.1 as compared to 9.1 in controls The percentage of positivity to Cimex 2nd antigen was 50.1 as compared to 18.2 in controls. On the other hand, the asthmatic patients showed different percentages of positivity to the common environmental inhalant antigens. The whole results were discussed. Of interest was the significant relation between the positivity in asthmatic patients to the antigens of Cimex abdominal extract and cotton dust extract. On the other hand, the precipitin tests gave negative results in both the asthmatic and control group.