The aim of the study was to develop a laboratory system to challenge mite allergic patients with physiological concentrations of Der p I in order to evaluate the efficacy of antiallergic drugs in mite allergic patients. A double-blind, placebo-controlled, cross-over study was designed with three consecutive sessions. Twelve patients with proven sensitivity to dust mite were treated with a single dose of dimethindene maleate in a FOAD formulation (4 and 8 mg vs. placebo) 12 h before a long-term challenge with mite allergen Der p I in the Vienna challenge chamber. Challenge was performed with a constant concentration of 40 ng Der p I per cubic meter of air for 4 h. Nasal parameters were recorded at 15 min intervals during long-term challenge. In comparison to placebo, dimethindene leads to a statistically significant reduction (p < 0.05) of the nasal response at both concentrations tested. The house-dust mite model in the Vienna challenge chamber thus proved to be a useful tool for drug investigations in mite allergies.