Major proteins from caprine milk were separated by preparative gel permeation and cation-exchange fast protein liquid chromatography and were characterized by flow injection analysis by electrospray ionization mass spectrometry. In addition, proteins from whole skim milk and whole casein were analyzed by coupling reverse-phase HPLC and electrospray ionization mass spectrometry by two different chromatographic methods. These methods successfully resolved the major caprine milk proteins and main casein variants. The experimental molecular masses of major milk proteins and variants were: 19,302 for kappa-CN 2P; 25,599 for alphas2-CN A-11P; 25,514 for alphas2-CN B-10P; 23,370 for alphas1-CN A-8P; 23,345 for alphas1-CN B-8P; 23,264 for alphas1-CN E-8P; 18,817 for alphas1-CN F-3P; 23,835 for beta-CN 6P; 18,181 for beta-LG; 14,180 for alpha-LA and 66,318 for serum albumin.