The aim of this study was to evaluate the role of Dermatophagoides pteronyssinus (Dp) in atopic dermatitis patients, using atopy patch test (APT) with Dp (extract 1). Twenty patients (males (m) = 9, females (f) = 11, mean age = 46.0 years, range = 19-78 years) with atopic dermatitis were involved in this study. The control group consisted of seventeen healthy subjects (m = 7, f = 10, mean age = 48.3, range = 24-64 years), with no personal or family history and no signs of atopy. Total IgE, specific IgE and a skin prick test were done for all subjects involved in this study. The atopy patch tests were performed with Dp (extract 1) in: 3,000, 10,000, 20,000 and 30,000 biological units per ml (BU/ml) concentrations using glycerol as medium. The total IgE was significantly higher in atopic dermatitis (AD) patients than in a control group with (p < 0.05). After the tests six of twenty patients (30%) had positive APT results in the last two concentrations (20,000 and 30,000 BU/ml). However, all the results were positive after 48 h (and 72 hours), while no positive results were recorded in the control subjects. According to our study, APT with Dp 1 in 20,000 BU/ml and reading time 48 h and 72 hours is to be recommended. The results suggest that APT may detect the trigger factor (Dp) in AD patients.