A 23-year-old healthy woman in her third trimester of pregnancy developed adult respiratory distress syndrome secondary to Blastomyces dermatitides. Pregnancy-related immunosuppression was believed to be responsible for the fungal infection. Following emergency delivery of the infant and a full course of amphotericin B therapy, the patient made an uneventful recovery. Although the fetal and maternal sides of the placenta demonstrated fungal spores, the child remained healthy. To our knowledge, this is the first report of blastomycosis-associated adult respiratory distress syndrome occurring during pregnancy.