Routine serum protein electrophoresis is recognized as the most reliable assessment of avian protein profiles in health and disease and has replaced biochemical determination of albumin and A:G ratio in the ability to predict abnormalities of clinical significance. The importance of considerable species differences to the overall interpretation of avian electrophoresis is well established and constitutes a continued challenge to the avian specialist and to the providing laboratories to continue the pursuit of species-specific, even age- and gender-specific, reference ranges. Patterns for various diseases continue to emerge as more scrutiny is applied to the use of this tool in avian diagnostics for overall health assessment as an adjunct to specific disease diagnosis and for both prognostic and therapeutic monitoring.