Background. A firm aetiology of lipothymia or syncope can be difficult to establish prehospitally. The aim of the study was to investigate patients initially assigned the diagnosis of lipothymia or syncope prehospitally and establish the aetiology of their condition either based on prehospital or in-hospital medical records. Methods. From May 1, 2006 to April 30, 2010, all patients receiving the diagnosis of lipothymia or syncope by the MECU were investigated. If admitted to hospital, the patients’ medical records were investigated to confirm the prehospital diagnosis. Results. Within 17980 MECU runs registered, 678 were assignments in which the patients were diagnosed with lipothymia or syncope (3.8%). 578 patients (85%) were admitted to hospital. 278 of the patients were discharged directly from the emergency department, while 271 were admitted to a ward. 112 patients refused treatment offered by the MECU or at the emergency department, died, or were left at the scene following treatment. 17 were lost to followup. Of all patients investigated, 299 were discharged with the diagnosis of lipothymia or syncope. 250 patients were discharged with other diagnoses. Conclusions. In 44% of the patients presenting with lipothymia or syncope, no other diagnosis was established at the hospital, and no explanatory aetiology was found.