Protein electrophoresis is commonly used to assess the different protein fractions in vertebrates. This information can provide important clinical information regarding the health status of an individual patient or a population of animals. The objective of this study was to evaluate plasma protein fractions of clinically normal, captive, male adult Nile crocodiles (Crocodilus niloticus) over a 12 month period. Blood was collected from the ventral coccygeal vein into heparinized syringes and immediately placed into vacutainer tubes. Samples were centrifuged, plasma removed, and the total protein content of each sample determined using the biuret method. Plasma proteins were separated using gel electrophoresis and scanned using a laser densitometer. No changes in total protein concentration were detected over time. Albumin values were significantly higher in December through March and lower from April through September. Beta globulin values were significantly higher in August through September and significantly lower in December through April. Gamma globulin values were significantly higher in March through May and again in June. The albumin/globulin (AG) ratio for January was significantly different from April through December. February and March AG ratios were both significantly higher than values collected in April through September. April through September AG ratios were significantly lower than were November and December AG ratios. The significant differences noted in the protein electrophoresis values suggest that seasonal changes occur in the healthy animals and should be taken into consideration when evaluating a clinical case involving a crocodilian.