[en] In developed countries, the prevalence of tuberculosis has evolved in an opposite direction as to the one of allergy over the last century. The immunological response is mainly Th1 in tuberculosis while it features a Th2 pattern in allergy. Vaccination with BCG in early life is associated with a reduction in the prevalence of allergy later in childhood. In an experimental mouse model of asthma, administration of BCG or killed Mycobacterium vaccae inhibits the sensitisation process as well as the bronchial inflammation and hyperresponsiveness that follows allergen exposure. In children and adolescents suffering from atopic dermatitis, subcutaneous injection of killed Mycobacterium vaccae attenuates the severity of skin lesions.