The aim of this study was to demonstrate the clinical effectiveness of treatment with specific immunotherapy using allergenic mite extracts modified with glutaraldehyde. The results showed an improvement both in clinical symptoms and a reduction in the complementary pharmacological therapy used. Several clinical "in vitro" and "in vivo" parameters were analysed during this study. The results obtained from the Nasal Challenge Test and the Skin Test (prick-test) were the most relevant. Patient tolerance to the diagnostic extract was increased in 45% of the patients, the result of which was registered in the Nasal Challenge Test. Evaluation of the results derived from the skin tests on conclusion of immunotherapy, showed a reduction in response in 55% of the patients. Progressive immunotherapeutic doses were applied at short intervals with no record of severe reactions.