This study was conducted to determine the effect of dietary sanguinarine supplementation on serum metabolites in growing pigs. A total of 240 (Yorkshire ´ [Duroc ´ Landrace]) pigs at 6 wk of age were randomly allotted to 3 dietary treatments, with 8 replicates per treatment and 10 piglets per replicate. The dietary treatments were as follows: the basal diet (BD) control group, the sanguinarine group (BD + 0.04 g/kg), and the antibiotic group (BD + 0.2 g/kg colistin). On d 7 and 14 after initiation of the treatment, BW, ADG, ADFI, feed efficiency (F/G), and serum levels of amino acids were measured. Dietary sanguinarine and antibiotic supplementation increased ADG, ADFI, and BW compared with the control group (P < 0.05). The data showed that the serum contents of amino acids, such as Gly, Ile, Lys, Met, Arg, Ala, and Thr, increased (P < 0.05) in the sanguinarine group compared with those in the colistin group and/or control group. These findings indicate a beneficial effect of dietary sanguinarine supplementation on the serum concentrations of some essential and nonessential amino acids, which improves growth performance of growing pigs.