The follicular form of bronchiectasis originally described by Whitwell (1) has been associated with adenoviral infection. The present study compares resected lungs from 16 patients with follicular bronchiectasis (in 10 of whom a nonviral etiology was identified) with those from eight patients with a nonfollicular histologic pattern. DNA isolated from sections of 45 paraffin-embedded lung samples was subjected to the polymerase chain reaction (PCR) using primers for the E1A region of the adenovirus genome and the human HLA DQ alpha gene. In situ hybridization (ISH) was performed on separate sections cut from the same blocks using a probe for the entire adenovirus 5 genome. E1A was demonstrated in six of eight patients (75%) with non-follicular bronchiectasis (non-FB) and in four of 16 (25%) with follicular bronchiectasis (FB) (p < 0.03, Fisher's exact test). The optical density ratio for the E1A product of PCR (ratio of E1A product from specimen to that from 1 pg adenovirus DNA) was significantly lower in FB than in non-FB (0.057 +/- 0.054 versus 0.365 +/- 0.223 [mean +/- SEM], p < 0.05). Moreover, the duration of symptoms of bronchiectasis in patients without E1A in bronchial specimens was significantly shorter than that of patients with positive E1A PCR products (3.09 +/- 1.44 versus 14.41 +/- 3.33 yr; p < 0.05). By ISH, adenovirus was demonstrated in three patients with FB and in two with non-FB (17.2 and 18.8% of tissue blocks, respectively; NS).(ABSTRACT TRUNCATED AT 250 WORDS)