It was aimed to compare semen and ions concentrations in the prostatic fluid of German Shepherd and Rottweiler dogs. Five semen collections of each dog (5 / breed) were accomplished and the following parameters assessed: total motility, vigor, concentration, percentage of sperm alive and normal morphology, as well as pH, cellular distribution and concentrations of calcium, phosphorus and magnesium were evaluated in prostatic fluid. Rottweiler dogs presented higher motility, concentration, percentage of alive Sperm and normal morphology than GS dogs. However, these dogs demonstrated higher levels of calcium in prostatic fluid. Differences were not observed concerning sperm vigor, phosphorus and magnesium concentrations, pH or the cellular distribution in prostatic fluid. It was concluded that Rottweiler dogs present better semen quality than German Shepherd dogs and a smaller liberation of calcium in prostatic fluid.