Reproductive problems in sows are the cause for at least 15% of the sow culls in Cyprus. The main cause of reproductive failure is urogenital tract infections (UTI), caused by pathogenic bacteria entering the sow’s reproductive tract, especially at risk times of farrowing and serving when the cervix is open (Almond and Richards 1992). Indigenous people have used cranberry preparations to prevent UTIs and other illness for centuries (http://www.cranberryinstitute.org/health/urinarytract.htm). An endogenous mechanism of the sow as protection against bacterial infections in the urogenital tract is the urinary pH, which can be manipulated by dietary means affecting the dietary anion-cation balance (Beker 1999). The objective of this experiment was to evaluate the effect of a dietary urine acidifier based on acidic acting substances (mixture of phosphoric acid and selected ingredients containing anions) and cranberry extract on sow urine parameters (pH, leucocytes and nitrates) and sow fertility parameters.