Epidemiological studies indicate a lower prevalence of asthma in Eastern than Western Europe. This study of the prevalence of asthma, chronic bronchitis, and respiratory symptoms was performed in three different regions of Estonia, a state incorporated in the Soviet Union until 1991. A postal questionnaire was sent to a random sample of 24,307 of the population aged 15-64 years. The response rate was 77.6%. The prevalence of physician-diagnosed asthma was 2.0% or considerably lower than in Northern and Western European countries. The prevalence of wheezing last 12 months, 21.7%, recurrent wheeze, 13.3%, and attacks of shortness of breath, 12.5%, were similar or even higher compared with prevalence rates found in the Nordic countries. The prevalence of physician-diagnosed chronic bronchitis was 10.7%, and was higher among women than in men, although the proportion of current smokers among men, 57%, was considerably greater than in women, 28%. A possible explanation to the high prevalence of respiratory symptoms also among non-smoking women may be exposure to environmental tobacco smoke in small, crowded Estonian homes. Diagnostic criteria based on the Soviet-time definitions is discussed as a possible explanation to the low prevalence of physician-diagnosed asthma and high prevalence of chronic bronchitis in Estonia compared with other Northern European countries.