The respiratory system is susceptible to unfavourable effects of biological and non-biological factors. In the protection against infectious agents, the immune system plays a crucial role thanks to close cooperation of specific (acquired) and non-specific (natural, innate) immune mechanisms. A non-specific response actively supports specific response mechanisms. This enables effective protection of our body against infections, both at the stage when pathogens reach the organism and after their penetration into tissues. A stimulation with microbial antigens leads to the activation of specific immunity mechanisms: humoral and cell-mediated responses. In the humoral response, specific immunoglobulins of various classes are involved to protect from recurrent infections. The knowledge of immunity development enables immune system stimulation with pharmaceutical products. The most common immunostimulants are non-specific and specific bacterial vaccines. The main goal of vaccines is the protection of healthy individuals against infections. Conventional prophylactic vaccines are immunogenic products. They contain a combination of extracts of various bacteria, usually ones that are aetiological factors of upper respiratory tract infections. Non-specific vaccines are administered to provoke a specific immune response towards antigens contained in the vaccine. They are bacterial immunostimulants acting mainly by stimulation and mobilisation of host defensive mechanisms. They improve antibacterial serum properties by increasing the level of natural antibodies. If needed, these reactions should be easily stimulated by a pathogen present in nature and should effectively neutralize or limit the disease. In patients who have been treated with a non-specific vaccine, decreased numbers of episodes of respiratory tract infections as well lower antibiotic intake were noted.