The role of Dermatophagoides (D.) pteronyssinus in atopic dermatitis (AD) was investigated by use of skin prick test (SPT) and total and specific IgE (RAST) to D. pteronyssinus. The study included 43 patients (17 male and 26 female), mean age 42.3 (range 19-77) years. All study patients met the Hanifin and Rajka criteria. Patients were divided into two groups: "pure" AD (n=27; 12 male and 15 female), mean age 46.3 (range 19-77) years; and AD with respiratory symptoms (AD+RS, n=16; 5 male and 11 female), mean age 38.4 (range 17-75) years. Control group consisted of 15 healthy subjects (7 male and 8 female; mean age 49.0, range 24-64 years), with no personal or family history and signs of atopy. Both patient groups had a higher total serum IgE than control subjects (p<0.05). In the "pure" AD group, SPT was positive in 5/27 (18.5%) and RAST to D. pteronyssinus in 4/27 patients. In the AD+RS group, SPT was positive in 10/16 (62.5%) and RAST to D. pteronyssinus in 8/16 (50%) patients. Concordance between SPT and RAST was observed in both groups; 80% of SPT positive patients were RAST positive. D. pteronyssinus was found to play an important role as a trigger factor in AD patients.