The first step and a crucial condition for the success of a control or eradication program for BVD (bovine viral diarrhea) is the identification and elimination of animals persistently infected with the virus. For this, besides detailed knowledge of the epidemiology, efficient diagnostic tests are necessary. This review summarizes the presently available diagnostic tests for detection of antibodies against the virus or for detection of viral components. Their performance and their applicability in eradication programs is discussed.