Passively acquired antibodies through colostrum will protect calves against etiological agents of neonatal calf diarrhea. Among them enteric diseases due to strains of Enterotoxigenic Escherichia coli (ETEC) are the most commonly occurring form of colibacillosis in newborn calves. Specific antibodies against whole ETEC cells and total immunoglobulin G in dam serum, colostrum and calf serum were determined. There were significant differences (P=0.0005) between antibody titers in normal and diarrheic groups, in which diarrheic group had a higher titer. Total IgG concentration in diarrheic calves (20.86 ± 0.49), their dams (23.48 ± 0.54) and colostrum (33.40 ± 0.50) was less than normal group (P=0.0005). There was a highly significant positive correlation between dam total IgG with calf total IgG (r=0.022; ratio=52.11). Colostral anti-E. coli antibody had a highly significant positive correlation with anti-E. coli in calf serum (r=0.345; ratio=0.62). Anti-E. coli antibody in calf serum had a highly significant negative correlati with total IgG of dam serum, colostrum and calf serum. While the level of anti-E. coli antibodies in diarrheic group was considerably higher than normal group, our findings reported here are in agreement that immunity to diarrhea also might be correlated with maternal cells or cellular components as well as cytokines which are transferred by colostrum to neonatal calves. Nevertheless, the level of maternally derived antibodies is a promising indicator for passive immunity and protection against diarrhea in neonatal calves.