Neonatal calves are born with no immunoglobulins (Igs) in the blood stream and rely on Ig from colostrum through passive immunity transfer. Unfortunately, transfer of passive immunity to neonatal calves is too often inadequate, resulting in excessive rates of morbidity and mortality. Natural zeolite is characterized by framework of linked tetra hydration enclosing open cavities in the form of channels, and cages with ion exchanger and adsorption capacity. In literature, there were reported that thermally activated natural zeolite (T-zeolite) could increase colostral IgG absorption and decrease susceptibility of neonates to infections (Sadeghi et al., 2004; Stojic et al., 1995). To our knowledge, little information is available concerning the effect of thermally activated natural zeolite on colostral IgG1, IgM and IgA absorption in neonates. Our experiment was designed to investigate the effect of thermally activated natural zeolite on colostral IgG1, IgM and IgA absorption in newborn Holstein calves.