Introduction. – The authors want to point out the contribution of complementary investigations performed to confirm the diagnosis of occupational asthma (OA) in bakers with a positive clinical history obtained by expert clinicians.Materials and methods. – The records of 27 subjects diagnosed between 1983 and 1999 as having OA of different degrees of severity were studied. The allergy workup in these cases had included skin tests for sensitivity to wheat flour, plus serological assays for specific IgE in 23 cases. All of them had had spirometry measurements, 19 had had bronchial hyperreactivity assessed, and a bronchial provocation test with flour had been performed in 11 cases. Follow-up data were available in 9 cases.Results. – Mean age of the patients was 27.9 years; 19 were bakers. Rhinitis, present in two-thirds of the cases, had first appeared after a mean of 3 years of exposure to flour, asthma after 6 years of exposure. Three cases had only intermittent asthma (grade I) while 19 had moderate persistent asthma (grade III). Sensitization to wheat was confirmed by serological assay in 21 of 23 cases and to barley in 14 out of the 16 cases tested. Three cases had spirometric evidence of permanent airway obstruction, and 14 out of 19 had non-specific bronchial hyperreactivity. The diagnosis of flour-induced asthma was confirmed by daily PEF measurements made at work and out of work in 14 cases. In 11 cases the diagnosis was confirmed by a bronchial provocation test, with an immediate reaction in all cases, a biphasic reaction in one case and a prolonged immediate reaction in 6 cases. Follow-up data were available for 9 cases, including 4 who had avoided flour completely after the diagnosis had been established. Those patients who had grade III asthma had not improved even when treated with inhaled corticosteroids. Professionally, most cases had either changed jobs (4 of 6 cases) or were unemployed.Conclusion. – The diagnosis of bakers’ asthma should be established stepwise: the decisional algorithm is based, first, on the clinical history obtained by a clinician expert in the field of OA and subsequently on the results of immunological investigations, PEFR measurements out of and at work and bronchial provocation tests. [Copyright &y& Elsevier]