An assay technique for determination of Human IgG in human plasma has been developed by utilizing Protein A bound to the modified cellulose matrices based on the strong affinity between protein A and Fc region of IgG. The pH values of loading buffer and elution buffer were 7.0 and 2.3 respectively. The cartridge used was 20 mm x 4 mm i.d. and detection was carried out with a UV monitor at 280 nm. The non-specific adsorption of two kinds of media has been studied. The media without hexyldiamine arm gives very low non-specific adsorption BSA. The calibration curve showed a good linearity (correlation coefficient > 0.9992) in the injected amount range of 9-70 micrograms for HIgG. The total time for separation and determination was within 5 min and the total time of rapid assay was within 30 s. Relative standard deviations of peak areas were 1.5% (n = 5) and 3.6% (n = 3) for HIgG in standard solution and human plasma respectively.