We report a patient with primary anti-phospholipid syndrome (APS) who developed pulmonary edema following sudden-onset pain in the left, lower back of the chest. Radiological examinations demonstrated fresh infarction of the left adrenal gland but no obvious thrombi in pulmonary arteries. The patient quickly recovered from pulmonary edema with anti-coagulation therapy alone. Primary APS may have caused adrenal infarction in the patient, leading to transient pulmonary edema via microthrombosis and/or excessive release of catecholamine.