The aim of our study was the evaluation of the clinical significance of allergic sensitization to cockroaches (C) in subjects with skin prick test (SPT) positivity only to mites, since we previously demonstrated a frequent association of SPT positivity between the allergens of these parasites. We studied 231 patients with mite related respiratory symptoms and living in the Naples area in order to obtain a highly homogeneous sample. All patients underwent anamnestic procedures, physical examination, SPT by using commercially available materials and an extract containing the whole bodies of three C. Specific C IgE assays were carried out only in C SPT positive patients. 34 of 231 subjects showed a SPT positivity to C allergens with a moderate/low degree of SPT responses and serum specific IgE levels. The results of this study confirm our previous report on the slight role of C as sensitizing agents of the respiratory tract in Southern Italy. Further studies should be carried out in subjects with a higher risk of environmental exposure by using better purified and standardized allergenic extracts. We suggest moreover to perform in vivo and in vitro diagnostic tests for C allergens in patients with perennial symptoms, especially in those with slight response to therapy, or potentially exposed to allergens of these insects.