PURPOSE OF REVIEW: Asthma is a common global respiratory disease characterized by airway inflammation. It is a heterogenous group of disorders with overlapping biological mechanisms. This review will discuss the current state of the use of biomarkers in asthma with an eye to the future. The identification of biomarkers has advanced our understanding of inflammatory pathways in asthma and aided in development of targeted therapies. However, even with similar inflammatory biomarkers, not all patients respond uniformly. Thus, further research into novel biomarkers in asthma is needed. RECENT FINDINGS: Recent literature highlights several key themes in biomarker research for asthma. Biomarkers can be derived from various sources, including sputum, blood, urine, and exhaled breath. Historically, studies have focused on eosinophilic inflammation, yet total blood eosinophil counts do not capture asthma pathology and treatment responses. Recent investigations explore eosinophil activity as well as eosinophil subpopulations based on surface protein expressions. Mast cell involvement, their mediators, and club cell secretory protein are further being examined across different asthma molecular phenotypes. SUMMARY: The complexity of inflammatory pathways in asthma, influenced by various factors, underscores the inadequacy of relying on a single biomarker at one time point. Continued research is essential to identify appropriate biomarkers.