Respiratory, gastrointestinal, sexually transmitted and other viral infections are very common and resistance to antiviral drugs is growing. The interest for new unconventional antiviral medications for control of virus diseases and symptom relief, as an alternative to those which are in use nowadays is growing worldwide. Among them probiotics are also mentioned. While the effect of probiotics on bacterial infections is relatively well understood (competition for nutrients, direct inhibition and effect on immune system), the research of antiviral activity of probiotics has only begun in recent times. The positive effects of probiotics against viral infections can be attributed primarily to the improvement of intestinal homeostasis and the gut barrier function. Specific probiotic strains are able to affect the mucosal or systemic immune response. They can modulate signalling pathways by improving immune response to virus. Specific strains of the genera Lactobacillus and Bifidobacterium can inhibit replication of influenza virus. L. rhamnosus GG decreases the possibility of the upper respiratory tract infections. In the case of acute gastroenteritis, L. rhamnosus GG, L. reuteri DSM 17938, S. boulardii CNCM I-745 strains can be used for the treatment of diarrhea. The improvements in patients infected with HIV, under the influence of probiotics (L. rhamnosus, L. casei) were assigned to modulation of the microbiota, reduction of the inflammation and improvement of physical and immune integrity of gut mucosa. Lactobacillus and Bifidobacterium also proved to be effective in viral sexually transmitted diseases.