The changes in serum levels of immunoglobulins G, M and A of dairy and beef calves of well-managed herds were monitored from birth to 14 days post partum using single radial immunodiffusion. Serum levels of all three immunoglobulin classes reached its peak at 24 hours in both groups of calves after birth, at which time there were very high levels of each immunoglobulin present. The mean IgM and IgA levels of the two groups became same at 6 days and 8 days of age, respectively but the mean IgG level of beef calves was approximately twice that of dairy calves throughout the experiment.