Supplementing swine diets with Mg has been shown to have beneficial effects on pork color and to decrease the incidence of PSE pork. Research has demonstrated that supplementing swine diets with Mg decreases blood cortisol and catecholamine concentrations and produces visibly calmer pigs after long-distance transportation. This study was to determine the effects of long-term dietary supplementation of magnesium and short-duration transportation on performance, stress response, postmortem metabolism, and pork quality. Thirty-six pigs in 6 pens were fed either control diet or control diet supplemented with 2.5% magnesium mica (MM) during early-finisher (44 to 68 kg of body weight), and late-finisher (68 to 103 kg) periods. At the end of 71-d feeding trial, 12 pigs from each dietary treatment were selected randomly and subjected wither to no stress (NS) or 3 h of transportation stress (TS). Dietary MM had no effect on average daily gain or feed intake; however, feed efficiency was improved during the early-finisher period when pigs were fed MM-supplemented diets. Plasma glucose concentrations were increased in TS pigs fed control diet, but transportation did not affect plasma glucose in pigs fed 2.5% MM. Transportation increased lactate, cortisol, and glucose concentrations, which were not affected by dietary MM. The LM from TS pigs fed MM had higher initial and 45-min pH values than the LM from NS fed control diet. Neither MM nor TS altered the color or water-holding capacity of the LM and semimembranosus. The transportation model elicited the expected changes in endocrine and blood metabolites, but dietary MM did not alter the stress response in pigs.