A computerized micro-ELISA system is described which features rapid and simple procedures for sample storage and transfer, plate washing and calculation of results. Calculations are performed by a Commodore Pet desk computer interfaced with a Titertek Multiskan micro-ELISA plate reader. Up to 1200 analyses per day can be performed by one person. Its application to the measurement of total immunoglobulin isotype and class specific antibody to parainfluenza type 1 (Sendai virus) in mice is described.