Nasal smears for eosinophils obtained by nose blowing and/or posterior nasopharyngeal swabbing were stained with Wright's or Hansel's stains and read in three groups of children aged 4 to 15 years: 65 with seasonal allergic rhinitis, 42 with perennial rhinitis and negative skin tests, and 70 nonallergic controls. Of smears obtained by either or both methods, 69%, 11%, and 7% were positive (greater than or equal to 4%) in the three groups, respectively. Almost identical results were obtained using only the nose-blowing method. In children with seasonal nasal symptoms, the nasal smear for eosinophils appears to be a reliable diagnostic test with moderately high sensitivity and high specificity.