BACKGROUND AND STUDY OBJECTIVES: Alpha1-antitrypsin (AAT) deficiency is common but under-recognized. A 1994 mail survey showed a long delay between the onset of symptoms and the initial diagnosis of AAT deficiency. In 2003, we carried out a similar mail survey of AAT-deficient individuals to determine whether any delay in diagnosis experienced by individuals with a more recent diagnosis had become shorter. We also determined whether individuals living near medical centers with an expressed interest in AAT deficiency experienced shorter diagnostic delays than those living at a distance. METHODS: Results from mail surveys of two different cohorts were compared: a 1994 survey of 304 individuals with severe AAT deficiency and a 2003 survey of 1,953 AAT-deficient individuals. In the 2003 survey cohort, diagnostic delay intervals were analyzed by calendar year of initial diagnosis, rural vs urban residence, visit to a liver or lung specialist within the last year, and living within 50 miles of a medical center with particular expertise in AAT deficiency. One thousand nine hundred fifty-three individuals responded to the 2003 mail survey (37.4%). RESULTS: In the 2003 cohort, the mean +/- SD diagnostic delay was 5.6 +/- 8.5 years, compared with 7.2 +/- 8.3 years for the 1994 cohort (p = 0.002). In the 2003 cohort, younger patients and male patients experienced shorter diagnostic delays than older patients and female patients (p < 0.0001 and p = 0.007, respectively). For example, the delay was 6.5 +/- 8.8 years for those born in the 1940s, as compared with 0.43 +/- 1.08 years for those born after 1980. Neither urban residence nor living near a center with expertise in AAT deficiency were associated with a shortened diagnostic delay interval. CONCLUSIONS: Although these results show some improvement in the mean diagnostic delay in the 9-year period separating the two studies, under-recognition of AAT deficiency persists. Diagnostic delay of AAT deficiency is longer in women and in older individuals. Educational efforts are underway to enhance clinicians' diagnostic suspicion of AAT deficiency and permit earlier diagnosis and attendant benefits.