Introduction: Antisynthetase syndrome (ASS) is characterized by the presence of anti-Jo-1 antibodies in conjunction with clinical findings of fever, polymyositis-dermatomyositis, and interstitial lung disease (ILD). Inflammatory myopathies carry a high risk of malignancy, but this association is less well outlined in ASS. We present the case of a patient with ASS who developed non-Hodgkin's lymphoma with acute hypoxemic respiratory failure. Case Presentation: A 44-year-old female with ASS presented with acute hypoxemic respiratory failure. She was empirically treated with broad-spectrum antibiotics for a health care-associated pneumonia; however, she failed to improve. Chest computed tomography revealed extensive bilateral ground glass opacities as well as extensive mediastinal and axillary lymphadenopathy. Infectious workup was negative. A surgical lung biopsy revealed peripheral T-cell lymphoma (PTCL). The patient was started on chemotherapy with complete resolution of hypoxemic respiratory failure. Conclusions: Malignancy is very rare in the setting of ASS; and our case illustrates the unique presentation of PTCL in ASS. In addition, lung involvement in PTCL is variable (incidence ranging from 8% to 20%); and in this case, bilateral multifocal consolidation was biopsied and proven to be PTCL involving the lungs. This case highlights the rare noninfectious conditions that can present as acute hypoxemic respiratory failure in the setting of ASS.