Asthma and chronic obstructive pulmonary disease (COPD) are two very common chronic lung diseases in the general population and are traditionally viewed as two distinct disease entities that can be easily differentiated by clinicians in the majority of cases. Both of them are characterized by a combination of multifactorial inflammatory processes and airway obstruction. In both diseases, the complexity of inflammatory processes affects the variable response to the given treatment among and scientific community, there is no doubt that despite the similarity between the two diseases and their affiliation with the group of obstructive lung diseases, the asthma treatment is different from COPD since the bronchoconstriction is usually reversible in asthma when on the other hand, COPD is characterized by progressive deterioration toward constant obstruction. Lack of distinction between these two diseases can lead to incorrect treatment that may even cause harm. In recent years, the understanding has begun to form that there is a significant overlap in both the pathological and functional aspects of asthma and COPD, especially among the elderly population where characteristics of the two diseases can be found simultaneously and thus the concept of Asthma COPD overlap (ACO) was born as a new diagnosis. ACO patients have been shown to experience higher rates of exacerbations, higher healthcare utilization, and worse health-related quality of life but unfortunately, the systematic exclusion of patients who did not meet the criteria for pure asthma or COPD from the clinical trials has resulted in the fact that the information which available today regarding prevention, the understanding of risk factors and prediction for the development of ACO among patients with long term and uncontrolled asthma, is limited. As a result, the adjustment of treatment for these patients is not optimal. Due to the facts outlined above, the purpose of this review is to summarize the main points of the most updated information that have concluded based on oriented studies that have been done with the ACO population of patients and to suggest additional lines of thought to cover the information gaps based on available data about asthma and COPD patients who share similar criteria to ACO patient. In hope that this paper will serve effectively every physician who might need to provide care for this spectrum of patients.