Presently, there are 6 biologic agents available for treatment of asthma. Each of these agents has undergone robust clinical trials in their approval programs. Such studies rely upon very rigid entry criteria that may not translate to real-world efficacy. Thus, exploring the efficacy of these agents in a larger, more heterogeneous, population brings a sense of comfort regarding their efficacy in the real-world. This review explores the available literature regarding the use of biologics in the real world, with a focus on markers of likely response to therapy.