Respiratory tract infections (RTIs) are a major cause of morbidity and mortality as well as high treatment costs, especially in developing countries like India. They are also a major cause of absenteeism from school and work.Hence, they need to be managed appropriately. If left untreated, they may result in complications, which can at times be potentially life-threatening. Antibiotics are often prescribed to treat respiratory tract infections such as acute sinusitis, acute pharyngitis, pneumonia and acute exacerbations of COPD. But, recurrence still occurs.Indiscriminate and inappropriate use of antibiotics has led to development of bacteria that are resistant to many commonly used antibiotics. This has left clinicians with limited therapeutic options.In view of the rising incidence of antibiotic resistance, the high treatment costs, prevention of recurrent infections is perhaps the answer. This can be done by vaccinations, but vaccines do not protect against all bacterial respiratory infections.Immunostimulants derived from bacteria may have a potential role in the management of recurrent respiratory tract infections. They have been demonstrated to increase the efficiency of immune system response, via both a specific as well as a non-specific effect on the cellular and humoral mechanisms. Bacterial lysates are mixtures of bacterial antigens obtained from different inactivated pathogenic bacteria. Polyvalent mechanical bacterial lysates (PMBL) are produced by mechanical lysis of the bacteria, including those that cause respiratory tract infections.Several studies have evaluated the role of PMBL in preventing respiratory tract infections and have demonstrated a protective effect and cause significant reduction in symptoms related to respiratory infections. PMBL is an effective treatment as it reduces the need of antibiotics and shortens duration of illness as well as that of hospitalization. It is also well-tolerated.