Blastomycosis is the infection caused by the dimorphic fungus Blastomyces dermatitidis. The fungus was believed to be limited in distribution to North America but is found in Africa and northern South America, too. The exact natural habitat of B. dermatitidis is still uncertain with only rare reported isolation of the fungus from the environment. The inability to recover the organism from nature along with the absence of both a reliable skin test antigen and a sensitive serological test have significantly restricted our understanding of the epidemiology and the full clinical spectrum of blastomycosis. An accidental laboratory infection and several common source epidemics have enabled us to recognize that blastomycosis may be a self-limited pulmonary infection. Endogenous reactivation and opportunistic infections have been newly appreciated as clinical presentations of blastomycosis. This report will review blastomycosis with particular emphasis on these recent developments.