Pica is defined as the appetite of the animals for non-feed substances, such as wood pieces, soil, bone, or hair. Animals with hair-eating disorders can bite and pluck hair from their bodies or other animals, causing alopecia and skin injuries. In the present study, it was aimed to investigate the total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI) levels in buffalo calves that ate each other’s hair. The study included 28 calves from a buffalo herd of 110 animals, including 22 buffalo calves with hair-eating symptoms (Group 1) and 6 calves without any hair-eating symptoms or signs of any disease (Group 2), aged 1–6 months. Blood samples were collected from the animals’ jugular veins to measure the TAS, TOS and OSI levels. Serum mean TOS and OSI levels of Group 1 were significantly higher than Group 2. In conclusion, the oxidative/antioxidative balance in the buffalo calves with hair-eating symptoms shifted in the direction of oxidation.