Objective. We wish to briefly review current knowledge of non-Hodgkin lymphomas ((NHL) with special emphasis on aspects of interest in ophthalmology, otorhinolaryngology and neurology. Development. We analyze the historical evolution of the classification of the NHL and refer to that recently devised by the World Health Organization. Amongst the numerous conditions forming part of this group of disorders we refer to the main data (clinical, immunophenotype, cytogenetics and of molecular biology) relative to the five most important types: 1. Follicular lymphoma; 2. Diffuse large cell lymphoma; 3. 'Mantle' cell lymphoma; 4. MALT lymphoma (mucosa associated lymphoid tissue), and 5 Peripheral T lymphoma. Then we describe the types and clinical forms of NHL in ophthalmology, otorhinolaryngology and neurology. Finally we consider the recent advances in prognosis (international index, biological markers) and treatment (new types of polychemotherapy, eradication of Helicobacter pylori, transplant of hemopoietic progenitors, monoclonal antibodies and anti-sense treatment of these conditions. Conclusions. The NHL form a group of conditions in which the annual increase in recent years has been over 4%. With considerable frequency these rumors are found from the beginning or during their course in otorhinological and ophthalmic tissues, or in the nervous system; in the latter case, apart from direct tumour expression they may also cause paraneoplastic manifestations.