The number of studies on the prognosis of bronchial asthma (BA) is rather limited. The aim of the study was to determine the evolution of BA in a long-term 12-year follow-up and to investigate possible contributing factors. One hundred and sixty-three patients who visited the Out-patient Clinic for BA from 1989 to 1993 (Visit 1) were included in the study. They were re-evaluated during 2003-2005 (Visit 2). At both visits, the patients filled in a special questionnaire, underwent skin tests, spirometry, methacholine challenge and they were classified into three severity groups according to GINA of 1992 as: Mild, Moderate, and Severe asthma. At Visit 1, 95 (58.3%) patients were classified in the mild asthma group, 45 (27.6%) in moderate and 23 (14.1%) in severe; whereas at Visit 2, 107 (65.6%) patients had mild asthma, 44 (27%) moderate and 12 (7.4%) severe. At Visit 1 asthma severity was associated with male gender, younger age, and the absence of rhinitis. At Visit 2 on the other hand, asthma severity was associated with older age, longer duration of disease, smoking and again the absence of rhinitis and increased BHR at both visits. Inhaled corticosteroid use correlated with improvement in lung function. Long-term prognosis of BA was good and outcome was favorably influenced by male gender, early and mild onset of disease, absence of smoking and presence of rhinitis.