Serum protein electrophoresis has gained importance in avian medicine during the past decade. Interpretation of electrophoretic patterns should be based on species-specific reference intervals and the electrophoresis gel system. In this study, serum protein electrophoresis by using high-resolution agarose gels was performed on blood samples collected from 105 falcons, including peregrine falcons (Falco peregrinus), gyrfalcons (Falco rusticolus), saker falcons (Falco cherrug), red-naped shaheens (Falco pelegrinoides babylonicus), and hybrid falcons, that were submitted to the Dubai Falcon Hospital (Dubai, United Arab Emirates) between 2003 and 2006. Reference values were established in clinically healthy birds and compared with values from falcons infected with Aspergillus species (n = 32). Falcons with confirmed aspergillosis showed significantly lower prealbumin values, which is a novel finding. Prealbumin has been documented in many avian species, but further investigation is required to illuminate the diagnostic significance of this negative acute-phase protein.