Objective: To investigate the incidence of multiresistant bacteria in patients treated in foreign hospitals and repatriated by international interhospital air transport. Methods: This was a prospective epidemiologic study on patients who were hospitalized in a foreign country and repatriated to a hospital in their home country by international aeromedical transport on scheduled airlines or ambulance jets. The study was carried out by the Department of Pediatrics, Department of Medical Microbiology, University Hospital Frankfurt, Germany, and MedCall Germany, the organizing company for repatriation. One hundred and three patients, who were hospitalized abroad, required repatriation by international interhospital air transport and met the entry criteria. Results: Four hundred and eighty-three swabs from brow, nose, ear, throat, groin or axilla were taken from 103 patients, mean age 62 years. They were transported from southern and eastern European countries, Morocco, Egypt, Ghana, Tunisia, Pakistan, the United States and the Bahamas to destinations in Germany, the UK, Belgium, Switzerland, the United States and Japan. Forty-four patients were in an intensive care unit (ICU) for 6.5 days (median) prior to transport. Forty patients received antibiotics at the time of repatriation. Acinetobacter, Enterobacter, Pseudomonas, Proteus, Staphylococcus aureus and Candida were found. Methicillin-resistant Staphylococcus aureus (MRSA) was found in three patients (3%), ventilated for 17 days, and treated in the ICU for a median of 23 days. In 2 patients, multiresistant Acinetobacter baumanii and multiresistant Klebsiella pneumoniae were found. Conclusions: Bacterial colonization of patients undergoing international interhospital air transport does not differ from that of patients in a European hospital. Multiresistant bacteria, especially MRSA, were found only in ICU patients. There is no elevated risk of transmission of multiresistant bacteria in this patient group compared to other patients treated in hospital, especially in ICUs.