Conjunctivitis accounts for a significant share in the structure of eye disease. The reasons for their occurrence are very diverse. At first glance, it seems that such a disease as conjunctivitis does not cause difficulties in making a diagnosis. However the wide variety of its clinical forms and the need for strictly specific treatment in some cases, in addition to modern laboratory diagnostics, requires careful collection of anamnesis, sufficient clinical experience, and knowledge of related medical specialties. In this case the probable etiology, mainly of acute conjunctivitis, can be established by anamnesis, a set of clinical symptoms observed in the dynamics of its development. In other words, each of the acute infectious or allergic lesions of the eyelid mucosa is characterized by its own symptom complex, while the effective treatment in such cases is specific therapy (antibacterial, antiviral, anti-allergic, etc.). Differentiation of various forms of conjunctivitis is usually based on the assessment of the nature of the discharge, the localization of follicular hyperplasia, and lymphadenopathy. At the same time, the patient's gender and age, living and working conditions, concomitant diseases, contact with an infectious patient, etc. are taken into account. As for chronic forms of mucosal inflammation, in contrast to acute conjunctivitis, they are characterized more by subjective complaints of patients than by objective changes. Since it is often not possible to establish their etiology from the biomicroscopic picture and other data due to the erased clinical picture, it is often necessary to resort to laboratory diagnostics to verify chronic conjunctival ophthalmic infections. Key words: conjunctivitis, clinical picture, diagnosis.