This paper was aimed at the presentation of difficulties in the interpretation of bluetongue (BT) diagnostic RT-PCR results in cattle. The possible role of cattle vaccination with commercial vaccines in the yielding a number of positive, real time RTPCR results was discussed. Also the relationship between the RT-PCR Ct value and the potential infectivity of an animal showing RT-PCR positive result was described to address the question of BT virus transmission between animals under intracommunity trade. Even weakly positive RT-PCR result can cause the significant alarm in a country that is free from bluetongue. The persistence of BT virus in a host animal, versus the RT-PCR positive result, in relation to the time elapsed from natural infection or vaccination with inactivated vaccine, was highlighted.