The objective of this study was to demonstrate that bovine neonatal pancytopenia (BNP) can be prevented when intake of maternal colostrum is prevented in a dairy farm with verified BNP cases. A group of 30 female calves was fed with a colostrum substitute instead of maternal colostrum (group A) whereas the control group of 30 female calves was fed with the colostrum of their own mothers (group B). The female calves were randomly assigned to groups A or B. All 60 calves were daily blood sampled in the first eleven days of life, afterwards up to the age of three weeks one blood sample was taken every other day. All blood samples were analyzed for thrombocyte and leucocyte counts. In addition, 113 calves of both sexes, which were born during the trial period, were blood sampled once at 6-10 days old. In group A, no BNP positive calf was verified. In group B, eight calves with a significant decrease of thrombocyte and leucocyte counts were observed. Only one of these eight calves had clinical signs consistent with BNP and the other seven calves were classified as subclinical BNP cases. Of the other 113 contemporary calves, eleven animals had clinical signs of BNP accompanied by a decrease of thrombocyte and leucocyte counts and four of these eleven calves died due to BNP. Our results revealed that replacement of maternal colostrum can prevent subclinical and clinical cases of BNP as well as losses due to BNP in a dairy herd with verified BNP-cases and in addition, that colostrum from these cows was the major risk factor for BNP in this dairy herd.