We investigated the prevalence of atopy by 4 different criteria (personal and family atopy, atopy by prick test and by serum IgE levels), and sensitization to wheat flour and alpha amylase in a group of trainee bakers and in a group of trainee graphic artists as controls (baseline check-up). The follow-up was performed 6 months later only among trainee bakers (90 cases), based on an updating questionnaire and on repeated skin prick test with wheat flour and alpha amylase extracts. Trainee bakers and controls were similar with respect to age, number of smokers, atopy evaluated by 4 different criteria, and detection of serum IgE (RAST) and IgG specific to wheat flour. Positive skin prick test to wheat flour (4%) and alpha amylase (1%) were found only among trainee bakers. At the baseline control 4 students (4.4%) complained of respiratory symptoms when working with wheat flour (WRS). At the six month follow up 6.6% of the trainee bakers complained of WRS: 3.3% had persistent symptoms, 3.3% were new cases and 1.1% had become asymptomatic. Five cases (5.5%) were skin positive to wheat flour or alpha amylase, but only one was unchanged, while 4.4% were new cases and 3.3% turned negative. None of these changes was statistically significant (McNemar test). The trainee bakers complaining of WRS at the baseline or at follow-up (7 cases, when compared with the non-symptomatics, showed a higher prevalence of personal atopy and skin sensitization to occupational allergens; there were no differences, however, with regard to atopy by prick test, IgE levels or the presence of wheat specific IgE and IgG. The trainee bakers skin positive to the occupational allergens (8 cases) showed prevalences of personal atopy and atopy by prick test significantly higher than trainee bakers skin negative to wheat flour or alpha amylase (p < or = 0.01). Evaluating wheat flour specific IgE and IgG in the serum of trainee bakers and controls provided us with more information about the specificity of such tests and suggests caution in attributing the presence of these immunoglobulins in the serum to specific occupational exposure or to specific occupational sensitization. A six-month follow up is likely to be too short an interval to observe significant changes in work-related symptoms and in skin sensitization to occupational allergens. The results, however, emphasize the important role of personal atopy as a predisposing factor in the development of occupational disease among trainee bakers.