To evaluate the correlations of the serum leptin with lipids, lipoproteins, and thyroid hormones in water buffalo (Bubalus bubalis), the serum concentration of leptin and its correlations with cholesterol, triglyceride, total lipids, very low-density lipoproteins (VLDL-cholesterol), low-density lipoproteins (LDL-cholesterol), high-density lipoproteins (HDL-cholesterol), and triiodothyronine and thyroxine hormones were measured in 80 clinically healthy water buffaloes. The serum concentration of leptin had no significant correlation with the measured lipids, lipoproteins, and thyroid hormones (p > 0.05). Separate evaluation of age groups showed that serum leptin had a significant difference between both sexes in buffaloes up to 2 years of age (p < 0.01). In male buffaloes, the serum concentration of leptin had a significant correlation with age (r = 0.545, p = 0.011) and there was a marginally significant difference in serum leptin between buffaloes up to 2 years of age and buffaloes more than 5 years old (p = 0.06). These relationships were not previously measured in water buffalo and were partially different from those of other species.