The use of egg yolk antibodies (IgY) instead of IgG from mammalian species may present several advantages in the development of routine diagnostic immunoassays. On the one hand, the animal suffering is reduced, as antibodies are obtained directly from the egg. On the other hand, the use of IgY avoids the rheumatoid factor interference. The rheumatoid factor interacts with IgG molecules in many immunoassays causing false positive results. Despite these advantages, IgY antibodies are scarcely used. As part of an aim to develop a diagnostic test based on IgY-latex agglutination, a preliminary study on some characteristics of the IgY-latex complexes is carried out. In this work, protein adsorption and desorption, isoelectric point, electrokinetic mobility, and colloidal stability are analysed. Results are compared to those obtained by IgG. Interesting differences are observed (which mainly arise from the difference in molecular structure between IgY and IgG), suggesting that IgY is a more hydrophobic molecule than IgG. In addition, colloidal dispersions of IgY-covered latex particles are more stable (at pH 8) than those sensitized by IgG.