Propylthiouracil (PTU) has been held responsible for diffuse alveolar hemorrhage (DAH) with positive antineutrophil cytoplasmic antibody (ANCA) and capillaritis. We describe a case of a 23-year-old pregnant female with Grave’s disease treated with PTU who presented with flu-like symptoms and progressive dyspnea. Open lung biopsy showed DAH without evidence of capillaritis. All serologies were negative. Five days after PTU withdrawal and intravenous steroid therapy, the patient improved dramatically. She remained symptom free without relapse 9 months after the episode. To the best of our knowledge, this is the first reported case of PTU-related alveolar hemorrhage with negative serologic markers and without capillaritis.