BACKGROUND: We evaluated the Test 1 (ALIFAX CO, Italy), an automatic erythrocyte sedimentation rate (ESR) analyzer which could eliminate one hour test interval and troublesome sample preparation. METHODS: Precision was analyzed with 10 repeat tests in 5 different ESR ranges. Storage effect was evaluated at refrigerated (4degrees C) and room temperature with samples in two different ESR range at 0 hour, 2 hours, 4 hours, 8 hours and 24 hours. And comparability study to modified Westergren method was done. Reference range assessment was done with 360 healthy population (180 males and 180 females). RESULTS: Within-run precision were varying with different mean ESR values; 19.00% at ESR 2.2 mm/hr, 5.97% at 13.2 mm/hr, 2.82% at 34.6 mm/hr, 4.45% at 66 mm/hr, and 2.42% at 115.6 mm/hr. Storage effect was significant at room temperature after 8 hours and no significant storage effect was observed even with 24 hour storage at 4degrees C. Correlation with modified Westergren method was good (y=1.198x-1.2729, r=0.965). Reference range for male was 2-19mm/hr, and that for female 2-26 mm/hr. CONCLUSIONS: Test-1 showed good precision, good correlation with modified Westergren method and minimal storage effect after 8 hours at room temperature and after 24 hours at 4degrees C and reference range was 2-19 mm/hr for male and 2-26 mm/hr for female. Analysis was rapid (20 seconds/test) and convenient with use of CBC samples without any processing to provide ESR as stat test. With its rapid analysis time and good precision, Test 1 could be used in clinical laboratory as 'stat' analyzer as well as routine analyzer.