Evidence-based national and international guidelines are largely aimed to guide in the diagnosis and treatment of asthma or COPD, but none addresses sufficiently mixed disease states of both disorders, which are ill-defined but very common in the daily routine clinic. This is a consensus report of a workshop on mixed disease. Asthma is characterized by a classical clinical history and physical exam, reversible airflow limitation and a high degree of bronchial hyperresponsiveness. In contrast, history (mostly smoker) and findings in typical COPD are different: COPD patients have little if any bronchial hyperresponsiveness and reversibility of the airflow limitation, respectively. However, beyond the full reversible airflow limitation which excludes COPD or mixed disease, none of these criteria are fully discriminatory. Patients with some of the characteristics of both diseases should be classified as mixed disease. A definitive diagnosis however, should only be assigned in a dynamic process. Once diagnosed the patient should be continuously re-evaluated according to the strength of the diagnosis, since the consequent treatment is important: COPD patients with asthmatic phenotype need early inhaled corticosteroids, even if their FEV1 > 50 %. Moreover, allergen avoidance can be indicated. On the other hand, asthma patients with COPD phenotype could benefit from anticholinergics or--if indicated--pulmonary rehabilitation. Mixed disease should be diagnosed as the coexistence of two distinct entities, i. e. asthma (allergic or intrinsic asthma, whichever is appropriate) and COPD.