Objective: To review the interaction of environmental factors with host conditions, including atopy, the potential resulting impaired upper and lower airway function, and diagnostic and therapeutic considerations in the athlete. Data Sources: OVID, MEDLINE, and PubMed searches were performed cross-referencing the keywords asthma, athlete, atopy, bronchospasm, exercise, pollution, and rhinitis. Study Selection: Articles were selected based on relevance to the subject matter. Results: Recent studies have yielded significant advances in our understanding of how intrinsic and extrinsic factors can potentially result in impaired function of the airways of athletes. Extrinsic factors include environmental exposure to temperature, humidity, aeroallergens, irritants, and pollution. Intrinsic factors include atopy, allergic rhinitis, asthma, and anatomical variants. These intrinsic and extrinsic factors can affect both the athlete's quality of life and athletic performance. However, uncertainty remains regarding relative contributions of these factors in explaining the high degree of bronchospasm seen in various populations of athletes with and without asthma, and no consensus exists regarding the most appropriate diagnostic and therapeutic modalities. Conclusions: Great variability exists in the presentation, laboratory findings, diagnostic maneuvers, and response to therapeutic measures among populations of athletes in different sports and among individuals. An improved understanding of the unique exposures faced by athletes in different disciplines, of the available tests for pursuing the appropriate diagnosis, and of the available therapies will allow the allergist to provide clinical improvement and allow the athlete to find relief and achieve his/her full potential.