**Abstract**

The immunological experience is treating osteomyelitis chronic forms at the Istituto Putti in Cortina starts in 1963 by introducing immunotherapy, applied by the progressive administration in growing doses of a staphylococci pool, that had been collected from some patients with bone infections by the same germ and then inactivated in an aqueous solution suspension. This therapy is coadjutant of antibiotics, surgical and hyperbaric therapy and not substitutive of these. This study ascertained indeed a reduction of the phagocytic activity as a whole, and especially the opsonisation activity It has been thought therefore that in immunotherapy more factors are involved; their principal property is to reduce the allergising effect and therefore to desensitise vs. the germ proteins and to increase the phagocytic activity. This condition, neither whose entity nor its lasting may be defined, does not appear to be unlimited. Obviously this desensitisation can be obtained also by the right antibiotic choice that, as already said mainly in acute forms, may develop their bactericidal properties and sterilise the focus. In the chronic forms it is possible to provoke this mechanism by carrying out a surgical toilette that restores the vascularization and stimulation conditions needed for a correct antibiotic action. Checks upon immuno-stimulation treatment termination clearly showed corresponding results between laboratory deficit corrected and clinical conditions bettering. The casuistry is based on 50 patients with hematogenic osteomyelitis, all under the age of 16, age at which the growth plate is still active, and 117 post-traumatic septic non-union, where this term was adopted for cases that showed a lack of non-solidification at 6 months after trauma. We have expressly made a distinction between hematogenic and post-traumatic forms, since the relationships between bacterial counts vs. host response do differ.

**Keywords:** immunotherapy, osteomyelitis, non union, psudoarthritis, vaccine
