Comparision was made of the results of manual microplate and automatic microplate determination for ABO system and Rh(D) antigen in 127 specimens blood of donated. A 1% cell suspension in 0.85% normal saline solution was used in the manual microplate and a 1.5% cell suspension in ethylenediamine tetraacetate/normal saline solution (EDTA/NSS) was used in the automatic microplate. Both techniques used anti-A 1 : 64, anti-B 1 : 32, anti-A, B 1 : 32 and anti-D 1 : 64. Identical results were obtained for each sample tested by both techniques, A Rh(D) positive 28 specimens, B Rh(D) positive 35 specimens, O Rh(D) positive 49 specimens, AB Rh(D) positive 13 specimens, B Rh(D) negative 1 specimen and O Rh weak D Ag 1 specimen. The modified microplate technique is simple, accurate and economical. The automatic microplate is suitable for a mass blood grouping and also reduces the risk of infection.