A method for the analysis of bovine immunoglobulin G (IgG) using sodium dodecyl sulphate capillary gel electrophoresis (SDS-CGE) has been described. Under the electrophoretic conditions employed, monomeric and dimeric IgG were readily resolved, as were light chain and heavy chain subunits, and heavy chain dimers in reduced samples. Molecular weights determined by SDS-CGE compared favourably with those measured by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and published values. Reproducibility of protein quantitation was achieved resulting in a relative standard deviation of approximately 13% and calibration was linear in the range of 0.2-3.5 mg ml-1 protein under the conditions used.