In the present study, the effects of IS900 PCR-confirmed subclinical paratuberculosis on serum beta-carotene and retinol concentrations in dairy cattle were investigated. A total of 30 multiparous, clinically normal, paratuberculosis non-vaccinated Holstein dairy cows, ages 3 to 9 years old were tested. Fifteen of the 30 cows were diagnosed as having subclinical paratuberculosis by IS900 PCR on faecal samples (Group 1). The remaining 15 cows, negative to three independent tests for paratuberculosis, were classified as the healthy control group (Group 2). Serum retinol and beta-carotene levels were analyzed by colorimetric assays on serum samples from all 30 cows. There were no differences regarding the serum retinol and beta-carotene concentrations between cows with and without paratuberculosis.  En el presente estudio se investigaron los efectos de la paratuberculosis subclínica en las concentraciones séricas de betacaroteno y retinol en ganado lechero. Se utilizaron 30 vacas lecheras multíparas y no vacunadas de raza Holstein, de 3 a 9 años de edad. 15 de las 30 vacas fueron diagnosticadas subclínicamente positivas a paratuberculosis mediante PCR (grupo 1). Las 15 vacas restantes fueron clasificadas como grupo control (grupo 2) que estaba sano. Los niveles de retinol y de betacaroteno del suero fueron analizados por análisis colorimétrico en todas las muestras. No hubo diferencias con respecto a las concentraciones de retinol y de betacaroteno de suero entre los grupos.