Lactobacillus rhamnosusBifidobacterium longumLactobacillus rhamnosusBifidobacterium longumLactobacillus rhamnosus Bifidobacterium longumThe present invention relates to the use of in combination with to manufacture a formulation to increase male fertility in a subject. In particular said strains are the strains CECT 8361 and CECT 7347. Additionally the formulation comprising the said strains CECT 8361 and CECT 7347 is also described.