An increased serum concentration of lactoferrin is associated with inflammatory disease, but there are few reported data on this aspect for lactating sows. Samples of blood and milk were collected from 17 lactating sows under minimum stress conditions and analysed for lactoferrin. Lactoferrin concentrations in serum and milk were positively correlated, being high after farrowing and steadily decreasing throughout 28 days of lactation. A positive linear correlation was observed between lactoferrin concentration and enzyme activities of alanine aminotransferase, lactate dehydrogenase, and hydroxybutyrate dehydrogenase in the serum indicating post-partum inflammation. Serum and milk lactoferrin concentrations, although closely correlated, may be regulated through independent systems activated simultaneously.