The atopy patch test (APT) was recently defined as an important tool in diagnosis of atopic dermatitis (AD) and also of rhinitis and asthma caused by hypersensitivity to the house dust mites. We evaluated 465 children (279 males and 186 females) aged 0.4-17.6 years (mean 6.6 +/- 3.8 years), by dividing them into four groups: group A, current AD (40 patients); group B, current AD with respiratory symptoms (156 patients); group C, past AD with respiratory symptoms (203 patients); and the control group, respiratory symptoms with no history of AD (66 patients). The APT was significantly more frequently positive in groups with current AD (groups A and B) or past AD (group C) than in the control group, while skin prick test (SPT) and radioallergosorbent test (RAST) were significantly more frequently positive in the control group. With multivariate analysis, for APT, significant differences were found in the comparison between group A vs group B (odds ratio (OR) 1.55) and between group A vs group C (OR 1.81). The mean age was significantly lower in group A than in groups B, C, and the control group and with less significance in groups C vs D. Children sensitized to mites with current or past AD, with or without respiratory symptoms, have a different response to diagnostic tests, which is characterized by a highly significantly more frequent positive APT in comparison with subjects who have respiratory symptoms but a negative history for AD, who show the common response to SPT and RAST.