Abstract: The objectives of this study were to: 1) determine the affect of supplemental lipoic acid (LA) on feed conversion and rate of gain on weanling pigs and 2) to evaluate the potential immunological benefits of supplementing piglet starter diets with lipoic acid. Twenty-one weaned gilts (d 21, 7 kg) were randomly allotted to three treatment groups: 1) Control, no supplemental LA (n=7); 2) LA-8, orally supplemented with 8 mg/kg body weight of LA per day (n=7); and 3) LA-15, orally supplemented with 15 mg/kg body weight of LA per day (n=7). Pigs were individually penned and treatments were administered orally for 12 days. Feed intake and body weights were recorded from d 0 to d 12. On d 11, pigs were nonsurgically fitted with jugular cannulae. On d 12, all pigs received a dose of 150 ug/kg of lipopolysaccharide (LPS). Blood samples were collected at 15 min intervals for 30 min prior to the LPS challenge and for 180 min after LPS challenge to monitor serum cortisol, tumor necrosis factor-alpha (TNF- ), glucoseand insulin. Additional whole blood samples were collected to determine total neutrophils and lymphocytes, as well as percentages. After the last blood sample was collected, all pigs were sacrificed for the collection of muscle and liver samples. Orally supplemented LA had no effect (P > 0.05) on average daily gain, average daily feed intake, or gain to feed ratios. No effect of LA was seen throughout the LPS challenge period (P>0.05) on serum cortisol or tumor necrosis factor- (TNF- ) concentrations. For serum glucose concentrations, differences among treatments were observed at –30 min pre-LPS such that serum glucose was lower (P<0.05) in the LA-8 and LA-15 groups as compared to the LA-0 group. A LA treatment effect (P<0.05) was observed between 45 and 165 min post-LPS, as LA-8 had higher serum glucose as compared to the LA-0 and LA-15 groups. From 120 until 165 min post-LPS, both LA-8 and LA-15 had higher serum glucose as compared to the LA-0 group (P<0.05). Serum insulin concentrations did not differ (P>0.05) among groups due to LA supplementation. There was a trend (P<0.15) for the LA-15 group to have lower glycogen content in the muscle samples as compared to the LA-0 and LA-8 groups. Glycogen content in the liver was lower in the LA-0 group as compared to the LA-8 group. On d 12, prior to the LPS challenge, the percentage of neutrophils was greater and the percentage of lymphocytes was lower (P<0.05) in the LA-15 group as compared to the LA-0 and LA-8 groups. Further research is needed to determine if supplemental LA may indeed be utilized as a beneficial immunomodulator in swine.