Jennings RT, Garriott OK, Bogomolov VV, Pochuev VI, Morgun VV, Garriott RA. Giant hepatic hemangioma and cross-fused ectopic kidney in a spaceflight participant. Aviat Space Environ Med 2010; 81:136–40.Commercial spaceflight participants are typically older than traditional astronauts and often have medical conditions that make medical certification for flight difficult. This case report considers a 43-yr-old spaceflight participant who planned a short-duration Soyuz flight to the International Space Station (ISS). While he participated in many hazardous activities such as parachuting, hang gliding, scuba diving, Antarctic and jungle exploration, and deep sea submersible operations, he knew that several of his medical conditions precluded serving as a career astronaut. At the time of his initial spaceflight prescreen examination, he was known to have previous bilateral photorefractive keratectomy (PRK) for myopia and a cross-fused left ectopic kidney that would be disqualifying for a career astronaut. During the evaluation for the left single cross-fused ectopic kidney, a giant hepatic hemangioma was also discovered. In order to medically qualify for flight, the giant hepatic hemangioma was surgically removed. This case summary investigates the implications of a single cross-fused left ectopic kidney and the decision process and treatment implications for spaceflight medical certification in an individual with an asymptomatic giant hepatic hemangioma.