The aim of the study was to determine the advanced cardiac life support (ACLS) knowledge level of residents and related factors in the departments of Anesthesiology, Emergency Medicine, Internal Medicine, and Cardiology in a university hospital. For this cross-sectional study, a total of 20 multiple-choice questions were prepared concerning several different topics, including: fatal dysrhythmias, oxygenation, ventilation and airway control, asystole, and pulseless electrical activity. Questions were given to residents before their periodic training meetings and collected in 30 min. There were 101 of 120 residents from four clinical departments (participation rate 84%) tested. Average point total and standard deviations of all residents were 66.3 +/- 17 out of 100 points. On a departmental basis, statistically significant differences were found in the knowledge level of residents (Emergency Medicine: 86.2 +/- 8.2, Cardiology: 66.7 +/- 12.9, Anesthesiology: 59.3 +/- 16.2, Internal Medicine: 56.1 +/- 13.5, F: 28.6, p < 0.0001). The factors that affect ACLS knowledge level of residents were "postgraduate ACLS training," "awareness of guidelines," and "resuscitation frequency." Postgraduate training and the frequency of ACLS practice seem to increase the ACLS knowledge level of residents. The present study emphasizes the necessity for a standardized systematic postgraduate ACLS training program for the residents of related medical disciplines. Further studies with larger groups are needed to investigate theoretical knowledge, resuscitation skill competency, and related factors.