herd Examination of 1078 pregnant cows in a neosporosis-endemic herd revealed that 382 sera (35.5%) were positive.A borderline titer of 1:200 was found in 95 sera (8.8%), 601sera (55.7%) had no antibody reactivity when diluted 1:200and, therefore, were considered negative (Table 1). Of the382 seropositive samples, 22% exhibited titers of 1:6400 orhigher.