Serum concentrations of amino acids, fatty acids, lipoproteins, vitamins A and E, and minerals in zoo giraffes (Giraffa camelopardalis) were compared to values obtained from free-ranging giraffes in an effort to identify potential nutritional differences in the zoo population. Zoo giraffes have a specific set of maladies that may be nutritionally related, including peracute mortality, energy malnutrition, pancreatic disease, urolithiasis, hoof disease, and severe intestinal parasitism. Dietary requirements for giraffes are not known; invasive studies used with domestic animals cannot be performed on zoo animals. Though domestic animal standards are often used to evaluate nutritional health of exotic animals, they may not be the most appropriate standards to use. Serum samples from 20 zoo giraffes at 10 zoological institutions in the United States were compared to previously collected samples from 24 free-ranging giraffes in South Africa. Thirteen of the zoo animal samples were collected from animals trained for blood collection, and seven were banked samples obtained from a previous serum collection. Dietary information was also collected on each zoo giraffe; most zoo giraffe diets consisted of alfalfa-based pellets (acid detergent fiber-16), alfalfa hay, and browse in varying quantities. Differences between zoo and free-ranging giraffes, males and females, and adults and subadults were analyzed with the use of a 2 X 2 X 2 factorial and Fisher’s Least Significant Difference (LSD) for mean separation. Of the 84 parameters measured, 54 (60%) were significantly different (P ≤ 0.05) between zoo and free-ranging giraffes. Nine (11%) items were significantly different (P ≤ 0.05) between adult and subadult animals. Only one parameter, sodium concentration, was found to be significantly different (P ≤ 0.05) between genders. Further investigation in zoo giraffe diets is needed to address the differences seen in this study and the potentially related health problems.