Background: Hydrogen peroxide (H2O2) is a common antiseptic that is available without a prescription in the United States, and it is indicated for minor dermal abrasion; mouth, gum, or dental irritations; and removal of oral secretion. Several other medical uses have also been described, including clot dissolution during endoscopic gastrointestinal evaluation, cleansing of orthopedic surgical sites, and bladder irrigation. However, these uses of H2O2, as well as high-dose ingestion, have been associated with a wide variety of medical complications, including but not limited to air pulmonary embolism and stroke. Case Presentation: Our patient is a 51-year-old female with a medical history of hypertension, familial, hypercholesterolemia, gallstones, depression, coronary artery disease (identified on calcium study because of familial hypercholesterolemia), nephrolithiasis, and recurrent cystitis. She required percutaneous nephrolithotomy and had H2O2 administered for clot dissolution. The clinical and temporal evidence would suggest a transient pulmonary air embolus after the intrarenal administration of or irrigation with H2O2, large amounts under high pressure. Conclusion: This represents the first reported incidence of air embolus as a result of intrarenal administration of H2O2.