*** Pyonephrosis caused by Salmonella sp. in a patient with polycystic kidney disease undergoing hemodialysis ***AIMS: This article reports a case of pyonephrosis caused by Salmonella sp. in a patient with polycystic kidney disease undergoing hemodialysis treatment.CASE DESCRIPTION: An elderly male patient previously diagnosed with polycystic kidney disease undergoing standard hemodyalitic treatment presented uronephrosis, evolving to pyonephrosis caused by Salmonella sp., and was successfully treated with ciprofloxacin.CONCLUSIONS: The polycystic kidney disease may have contributed to the bacteria’s attachment to the kidney, due to increase of permeability of the intestinal mucosa, easier bacterial translocation to bloodstream and its subsequent accommodation in the infected organ.