BACKGROUND: Considerable progress has been made over the past 15-years accommodating the need for accurate and precise immunologic assays on an automated system. A new enhanced chemiluminescence technology. The aim of the present study was to compare and evaluate analytical performances between Vitros ECi and AxSYM (Abbott Laboratories, Abbott park, Illinois, USA) System. METHODS: The study evaluated the following assays : thyrotropin (TSH), triiodothyronine (T(3)), throxine (T(4)), alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), hepatitis B surface antigen (HBs Ag), hepatitis B surface antibody (HBs Ab), hepatitis C virus antibody (HCV Ab) and human immunodeficiency virus antibody (HIV Ab). Using control material, pooled serum, 652 patients' sera and seroconversion panels, Vitros ECi and AxSYM were compared for linearity, precision and correlation. RESULTS: The coefficient of variations (CVs) of Vitros ECi with AxSYM showed below 5% for all analytes except low levels of CEA. Good linearity was observed for all analytes (p<0.01), revealing statistically relevant. Correlation equations utilized for analysis between Vitros ECi and AxSYM were : TSH Y=1.147X-0.1.1 (r=0.989, N=69), T(3) Y=0.739X + 15.262(r=0.933, N=77), T(4) Y=0.984X + 0.729(r=0.963, N=73), AFP Y=1.115X + 0.673(r=0.980, N=65) CEA Y=1.015X-0.261(r=0.996, N=69)(p<0.01), revealing statistically relevant. Agreement rates of patients' sera were HBs Ag 97.7%, HBs Ab 94.3%, HCV Ab 94.0% and HIV Ab 100%. Agreement rates of seroconversion panel's sera were HBs Ag 95.8% and HCV Ab 86.2%. CONCLUSIONS: Compared to the performance of AxSYM presently being used, the new Vitros ECi showed the good performance and considered as useful equipment for routine immunoassay in the clinical laboratory.