Introduction: The solitary plamocytoma of the bone (SPB) is the solitary manifestation of the multiple myeloma. It belongs to the oncological entity of non-Hodgkin lymphomas and comes with an uncontrolled proliferation of a malignantly transformed plasma cell clone. Plasmocytomas of the head and neck are rare and are mostly found in the soft tissue, solitary plasmocytoma of the jaw is a rarity. Patient and diagnosis: The 45- patient presented with an increasing swelling of the left temporo mandibular joint, which had developed during the last 3 weeks. The opening movement of the jaw was painful and reduced to a SKD of 20 mm. The patient showed a lateral deviation to the right side of 2 mm. The panoramic x-ray showed a 7x3 cm sharply bounded osteolysis hollowing the entire condylar processus. The MRI confirmed these dimensions and displayed the homogenous tumour mass. Results: The excision of the lesion was performed via pre-auricular approach. The major bony part of the condyle was replaced by necrotic soft tissue. The pathological appraisal diagnoses a plasmocytoma of the bone in an average stage of maturation. The further oncological therapy is exerted by the heamato-oncological department following standard protocols of chemotherapy and radiation. Conclusion: The solitary plasmozytoma of the jaw is a rarity; its prognosis is good with a 10 years survival rate over 75 %. Recurrent disease or the progression to a disseminated form of myeloma is generally possible and comes with a drastic pejoration of the prognosis. Keywords: Plasmozytom, solitär, Unterkiefer