Blastomycosis is not a common infection. The Centers for Disease Control and Prevention estimates the incidence in endemic areas to be one to two cases per 100,000 population. Yet, the consequences of missing the diagnosis can be significant, including not only an unfavorable clinical outcome, but also substantial distress to the patient as he or she faces potentially unnecessary tests and procedures while having to cope with the uncertainty of diagnosis. Understanding the various forms of this treatable infection, especially by clinicians who practice in endemic areas, is the first step to smooth diagnosis and treatment. Then, suspicion in patients whose exposure history and disease presentation put blastomycosis into the differential diagnosis should direct collection of adequate, and perhaps, multiple sputum specimens to be cultured and stained for fungal detection, including by Papanicolaou stain. Specimens from bronchoscopy and other more invasive procedures should also be appropriately collected and processed. With the proper knowledge and watchfulness, hopefully the true identity of this great masquerader will, in more cases than not, be promptly exposed.