ABSTRACT.- In 2021, bovine polyomavirus 1 (BoPyV1; Polyomaviridae, Epsilonpolyomavirus bovis) was associated with nephritis in an aborted bovine fetus in Uruguay, with renal lesions resembling those typical of polyomavirus-associated nephropathy of humans. Given that little is known about the epidemiology of BoPyV1 infection in cattle, we screened for BoPyV1 in urine samples collected in 2015-2017 from beef and dairy herds from 12 of the 19 departments in Uruguay. We tested for BoPyV1 by PCR in 156 urine pools and 249 individual urine samples from 42 herds. We detected BoPyV1 in 33 of 42 (79%) farms across 100% of the departments studied, in similar proportions in beef (22 of 30; 73%) and dairy (11 of 12; 92%) herds. At the animal level, BoPyV1 was detected in 80 of 249 (32%) animals; this frequency was significantly higher in dairy (51 of 119; 43%) than beef (29 of 130; 22%) cattle, and in cows (36 of 81; 44%) than heifers (32 of 121; 26%). BoPyV1 strains circulating in Uruguay have a high degree (98.7-100%) of sequence identity at the major capsid protein VP1, which is slightly lower (96.2-99.7%) than for strains from other countries. We conclude that shedding of BoPyV1 in the urine of dairy and beef cattle is prevalent and geographically widespread in Uruguay. © 2025 The Author(s).