Two in vitro assay systems to measure cell-mediated immunity in experimentally induced anaplasmosis in splenectomized and intact calves were compared. In intact calves, the cell-mediated cytotoxic assay detected a cell-mediated immunity response early, which subsequently decreased during the recovery phase of the disease, whereas the leukocyte migration-inhibition test was negative initially and became positive during the recovery phase of the disease. In splenectomized calves, the 2 test results were not as conclusive. Positive values with the cell-mediated cytotoxic assay were noticed later in the experimental period, but higher and persistent values were observed. The leukocyte migration-inhibition test was positive at various times during the experimental period. The 2 assay systems did not correlate.