We performed a prospective study to describe the broad spectrum of causes of chest pain in patients presenting to the emergency department and to compare the diagnoses in referred patients, self-referred patients and patients rushed in by ambulance. The final diagnosis in a consecutive case series of 578 chest pain patients was established after discharge from the hospital. The underlying disorders were grouped into cardiac, respiratory, gastro-oesophageal disorders, musculoskeletal pathology, somatization disorders, other diseases and unknown. For comparison of the frequencies of the disease categories the Chi-squared test was used. Out of 578 patients, 161 (27.9%) were self-referred, 369 (63.8%) were referred by the general practitioner and 48 (8.3%) were rushed in by ambulance. Cardiac diseases represented 51.7% of the cases, myocardial infarction and unstable angina 19% and 12.8% respectively Cardiac diseases were statistically significantly less common in self-referred patients (p<0.0005). Pulmonary diseases encompassed 14.2% of the population, followed by somatization disorders (9.2%), musculoskeletal pathology (7.1%) and other causes (4.3%). In 11.1% of the cases no definite final diagnosis could be established. Somatization disorders were significantly more frequent in self-referred and ambulance patients. Cardiac and pulmonary problems are the most frequent underlying disorders in acute chest pain patients in the emergency department. Somatization disorders and musculoskeletal pathology represented respectively 19.1% and 14.8% of the non-cardiac causes. The referral pattern influenced significantly the distribution of the disease categories with more cardiac and less psychiatric disorders in referred patients.