Abstract This study evaluated the association between serum parameters and feedlot performance, and efficiency measures of water buffalo for meat production. Seventy-five animals of three different genetic groups (GG:Jafarabadi, Mediterranean, and Murrah) were used, with means of initial body weight (BW) and age of 314±117 kg and 13±1.2 months, respectively. Animal BW were recorded at the beginning and every 28 days until the final of the efficiency period (EP; 84 days). Animals of each GG were allocated in collective pens provided with artificial shade and automatic feeder system to determine individual daily intake of diet and water offered ad libitum. Average daily gain (ADG, kg/day), dry matter intake (DMI, in kg/day and %BW) were evaluated. Efficiency measures [feed conversion ratio (F:G), feed efficiency (G:F), residual feed intake (RFI), residual gain (RG), and residual intake and gain (RIG)] were calculated considering 84 days of experiment. Blood samples were collected from the jugular vein on days 0, 56, and 84, and were evaluated for serum levels of leptin, glucose, insulin, cholesterol, triglycerides, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL) by commercial kits. Animals were clinically healthy and with no skin lesion, intestinal and blood parasites, as well as no diarrhea, urogenital or muscular abnormalities. Data were analyzed using the CORR procedure with partial command in SAS. There are some correlations between serum parameters and feedlot performance and efficiency measurements (P ≤ 0.05) as well as there are tendencies (P ≤ 0.10; Table 1). Furthermore, leptin, TRI, and lipoproteins serum levels are the parameters most associated with some performance and efficiency variables. In conclusion, although weak, the correlations suggest that there are alterations of serum parameters according to performance and efficiency and these parameters can be used as tools to assist in decision making within the buffalo production system. Supported by FAPESP (#2014/05473-7).