We measured urine pH from cows fed a prepartum diet containing polyhalite mineral as an acidogenic salt. At 21 d before expected calving date (ECD), cows were transferred from the far-off to the close-up group. The polyhalite mineral was incorporated into a pelleted concentrate to provide 500 g d^-1. Urine pH at -21, -14, -7, and 0 d relative to ECD was 8.26, 5.18, 5.12, and 5.15, respectively. These results indicate that a metabolic acidosis could be effectively induced when polyhalite mineral is included as an acidogenic source in close-up rations for pregnant and non-lactating dairy cows.