The purpose of this study was to establish reference intervals of the protein electrophoretic fractions and the acute-phase proteins hemoglobin binding protein (as determined by the haptoglobin assay) and C-reactive protein (CRP) and assess any possible correlations between varying age class, sex, location (Illinois or Michigan), year, or presence of snake fungal disease (SFD). Banked plasma samples were assayed from 130 eastern massasaugas from 2009 to 2014 in Illinois and Michigan. Snakes from Michigan had higher total protein (mean: 5.50 g/dl), albumin/globulin ratio (0.42), albumin (1.59 g/dl), and gamma globulins (0.55 g/dl) than from snakes in Illinois (4.72 g/dl, 0.29, 1.03 g/dl, 0.38 g/dl, respectively). Snakes in Illinois (22.19 g/ml) had higher CRP than snakes in Michigan (10.89 mg/ml). Adults had higher gamma globulins (0.47 g/dl) than juveniles (0.28 g/dl). Males had higher alpha-2 globulins (0.98 g/dl) and CRP (21.4 mg/ml) than females (0.85, 11.6, respectively). There were no significant differences in absolute plasma proteins in SFD-positive snakes, but the percentage of gamma globulins was significantly higher in positive snakes. Future research in this area can now build on this data to determine changes in population health over time or due to specific environmental or disease threats.