Results from the present study confirm the growthpromoting benefits of feeding an intensified milk replacer to dairy calves. Effects of the elevated plane of nutrition on immune variables examined in the present study were minimal. The number of circulating leukocytes and the composition of the PBMC population as well as this population’s general responsiveness and capacity to secrete IgM were not affected by diet. Relative to responses of calves fed the traditional MR, calves fed the intensified MR demonstrated reduced IFN-γ responses and elevated NO responses during the latter stages of the study. Aberrant NO production, however, can result in undesirable host tissue destruction.