A case of hypersensitivity pneumonitis (HP) following anthrax vaccination is described. The patient is a 39-year-old, previously healthy man on active duty in the US Marine Corps, in whom a urticaral skin rash and progressive dyspnea on exertion developed following subcutaneous anthrax vaccination. A diagnosis of bronchiolitis obliterans with organizing pneumonia was made from transbronchial lung biopsy samples after evaluation excluded multiple infectious and collagen vascular etiologies. This appears to be the first recorded case of HP following an anthrax vaccination; however, a case report of pulmonary and cutaneous vasculitis following hepatitis B vaccination has been reported in the literature and is reviewed.