Background.- Syncope is one of the common presenting complaints in the emergency department population which makes up to 3% of the total cases. Many diagnostic tests have been devised to evaluate these patients. There are not any well-established protocols as to which tests should be performed in order to evaluate etiologic causes of syncope. As a result, these patients generally undergo routine laboratory screening tests. This study aims to describe demographic characteristics of the patients referred to Dokuz Eylül University ED with the chief complaint of syncope and to investigate the usefulness of the diagnostic tests used to evaluate these patients.Design.- We examined data charts of 798 patients with final diagnoses that could be related to syncope referred to the ED in between 24.04.1998 and 31.07.1998 retrospectively. 156 of the 798 patients were eligible. The majority of the patients were consisted of middle-aged women. The most common causes of syncope were revealed to be vasovagal and psychogenic factors. Cardiac syncope was most commonly diagnosed in elderly patients and 27.6% of the patients was idiopathic.Results.- We could not find any usefulness of commonly ordered diagnostic tests such as Na, K, Cl, creatinine, glucose, CK, LDH, AST, total bilirubin, direct bilirubin, amylase, urinary b-HCG, occult blood in stool and ABG regarding decision to admit and establishment of diagnosis of syncope. However, factors that predict admission of patients include EKG abnormalities, cardiovascular examination, cardiac monitoring, neurologic examination and cranial CT in patients with neurologic deficits. In addition, tests that may be beneficial in determining admission to hospital are CBC, BUN, Ca.Conclusion.- As a conclusion, future research could reveal efficiency of various laboratory tests ordered in routine work-up of syncope patients which may help cut down substantial healthcare expenses.* Anahtar Kelimeler: Senkop, Acil servis, Laboratuar incelemeleri* Key Words: Syncope, Emergency department, Laboratory analyses