Diagnosis and immunotherapy with venom extracts of patients sensitive to Hymenoptera stings has led to the problem of improving the standardization of Hymenoptera venom products. Current methods of standardization use the Lowry protein determination and a radial-diffusion assay for hyaluronidase activity. This study demonstrates that the results of these analyses do not always correlate with the actual quantity of allergenic protein present in the extracts. A method of standardization is examined herein that uses polyacrylamide gel electrophoresis to quantitate phospholipase A, antigen 5, and hyaluronidase, the proteins that together comprise most allergenic protein present in the venoms. Also discussed in this study is the biochemical variability of phospholipase A and antigen 5 in the venoms of the different vespid species examined.