Patients presenting with Hodgkin's disease (HD) may show lung involvement characterized by contiguous spread from ipsilateral hilar lymph nodes. Lung consolidation or noncontiguous pulmonary involvement makes an alternative diagnosis more likely. This report describes a patient with HD in whom concurrent pulmonary blastomycosis was recognized only after chemotherapy had started and dissemination had occurred. Although Blastomyces dermatitidis may behave as an opportunist pathogen, there are no previous reports of blastomycosis in patients with HD. Undiagnosed active opportunistic infection at the time of diagnosis of HD may complicate staging as well as treatment. Biopsy of lung lesions with stain and culture for opportunistic pathogens should be considered in patients with newly diagnosed HD disease and atypical patterns of lung involvement.