In addition to several conventional methods for the detection of red cell antigens, the use of microplates has various advantages either as a solid-phase assay (enzyme immunoassay) or as native microplate. Microplates may also be used for the detection of red cell antibodies in 'pooled-cell solid-phase assays' of the second generation and for antibody screening. Blood donors and patients are the two main fields which are to be examined in immunohematology. There are various advantages in using the microplate in blood group serology: (i) if there is hardware already available, like sample processors and microplate readers, the use of microplates in blood group serology reduces the costs even if the equipment has to be purchased for this purpose only; (ii) low quantities of reagents are used in microplate assays; (iii) the application of bar codes on tubes and microplates guarantees the most security in sample identification; (iv) it is possible to investigate blood samples selectively depending on the available software if antibody detection is done as the sixth test beside anti-HIV, anti-HCV, HBsAG, lues antibodies and ALT, and (v) recording of data will be easy if electronic data processing is used.