Paratuberculosis was first reported in Spain in 1973 in sheep and in 1983 in cattle. Since then it has become evident that this infection is not rare, and that there is an increasing demand of laboratory testing. However, no estimate is available on the prevalence of the infecion in the whole country. The only detailed study on paratuberculosis prevalence covered only the north-central area of Spain comprising the Basque Country and adjacent provinces and reported a general prevalence of subclinical infection of 30% of individual cattle. In order to have at wider estimate, we carried out two studies based on the PCR detection of Map in bulk milk samples. In one the whole country was represented by a small number of samples (5x14) randomly taken from 14 out of the 17 Spain's larger adminstrative divisions. In the other, the same type of sample and processing was used to verify the former results on a more restricted area roughly corresponding to the Bay of Biscay coastal strip. This area contains 69% of cattle farms in Spain. In this study, 200 bulk milk samples were processed. All samples were frozen and stored at -20ºC until used. An IS900 PCR protocol was carried out on the centrifugation pellet of 10 ml of milk, and the products separated in an agarose gel. A band of 389 bp was considered a positive result which was confirmed by sequencing in a few cases. In the first bulk milk survey the sample proportion of PCR positive samples was 10% whereas in the second the frequency was 8%. Given the small sample size these estimates had a large error and therefore only had a value in setting the maximum estimated prevalence which was 47.6% and 19.3%, respectively.