Background. There are studies indicating that bronchial asthma is often underdiagnosed, while only a little research has been conducted as concerns overdiagnosing asthma. Objective. We aimed to estimate the number of patients who have been given the wrong diagnosis of asthma. Methods. All patients aged above 18 years who had visited two GPs during 1994 or 1995, with the diagnosis of bronchial asthma confirmed in the medical register, were examined by a specialist in allergies. Results. One hundred and twenty-three patients fulfilled the criteria for being included in the study. Eighty-six patients (70%) attended the examination. Of these, 51 (59%) had bronchial asthma, six (7%) asthma in combination with chronic obstructive pulmonary disease (COPD) and 29 (34%) no asthmatic disease. Conclusion. The study indicates that more accuracy is needed when diagnosing bronchial asthma.