The objective of this study was to assess the serological response against one of the valences included in the vaccine for the neonatal diarrhoea, the Labile Toxin (LT) produced by the ETEC. First of all, the IgG seroprofile was assessed using an ELISA against the LT antigen. Afterwards, to obtain the biological significance of these antibodies, the seroneutralization properties against the LT of swine sera were analyzed.