Neosporosis is one of the principal causes of reproductive problems in cattle worldwide. The aim of this study was to evaluate the occurrence of anti-Neospora caninum antibodies in cattle and dogs from dairy farms from the central northern region of Paraná state. Blood samples with and without EDTA were collected from 400 cattle and 46 dogs from 20 properties. Nested polymerase chain reaction (n-PCR) was performed on whole blood samples and indirect immunofluorescence reaction (IFR) on the serum samples (after clot retraction). Cattle and dogs with titers ? 100 and ? 50, respectively, were considered positive. Anti-N. caninum was detected in 20,1% (80/400) of cattle, with titers ranging from 100 to 1600. The n-PCR presented only two cattle positives (0.5%). Anti-N. caninum was detected in 19,6% (9/46) of the dogs, with titers ranging from 50 to 6400. The occurrence of antibodies against N. caninum obtained in the present study was similar to those in studies performed in other regions of Paraná and Brazil. The probability of detecting parasitemia in epidemiological studies is a rare event.