The evolution of the humoral responses of IgG and IgM against 29–35-kDa Toxoplasma gondii fractions from experimentally infected goats were studied and compared by ELISA with the use of whole T. gondii soluble extracts and 29–35-kDa electroeluted proteins as antigens. The IgM response to electroeluted proteins was detected from wk 1 to wk 3 postinfection, showing a similar evolution to that observed when T. gondii crude extracts were used as antigens. These results suggest that this group of proteins could be used for a more specific detection of anti–T. gondii IgM. In the same way, the IgG response was equivalent in both cases, although when 29–35-kDa T. gondii fractions were used as antigens, the level of specific IgGs reached a peak 2 wk before than when T. gondii crude extract was used. The detection by ELISA of anti–T. gondii IgM in goats does not seem to be affected by the presence of specific IgG in serum samples when 29– 35-kDa protein fractions were used as antigens.