We studied 40 children with one o more perennial allergic diseases (bronchial asthma, allergic rhinitis, and/or atopic dermatitis) to assess the value in our country of in vivo and in vitro tests more frequently used in the diagnosis of allergy, such as total serum IgE, specific allergen IgE (RAST) and prick skin test in patients sensitives to D. pteronissinus, D. farinae or both. All patients had positive prick skin tests. Total serous IgE was elevated in 95% of cases with poor correlation coefficient (r) between prick skin test reactivity and total serous IgE concentration with no statistical significance. On the other hand, 95% of patients showed a positive RAST with a correlation coefficient of 0.31 (p less than 0.05). We concluded that in our country clinical history and prick skin tests are sufficiently accurate in a reasonable way to make a diagnosis of allergic etiology in patients sensitives to mites of the house dust.