Whole safflower seeds of the Mexican variety Kino'76 with a protein content of 17.30% (dwb) were subjected to the processes of dehulling, defatting (n-hexane extraction) and debittering (70% methanol extraction) to produce four types of meals preparations: whole safflower meal, dehulled safflower meal, debittered, whole meal and debittered, dehulled meal with protein contents of 26.90, 66.93, 26.70 and 69.92%, respectively. The proteins of each meal were studied in detail by means of protein fractionation, gel filtration chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Osborne solubility fractionation of the protein of whole safflower meal showed that the amount of protein in the alkali soluble fraction was approximately 71% of the total and the alcohol soluble fraction did not contain any protein. After dehulling and debittering, the amount of protein in the alkali soluble fraction decreased by 30%, whereas the amount of protein in the insoluble residue increased by 12%. SDS-PAGE of the proteins of the water-, salt- and alkali soluble fractions revealed that they consisted of 8, 13 and 13 distinct subunits, respectively, with apparent molecular weights ranging from 14.7 to 88.0 kDa. The number of subunits and molecular weight distribution decreased as a result of debittering. Fractionation of the proteins of each meal by gel filtration chromatography followed by SDS-PAGE demonstrated that proteins of safflower seed are highly heterogeneous. The process of debittering caused major alteration of the molecular weight profile and subunit composition of the gel filtration protein fractions.