Allergic conjunctivitis, also known as an ocular allergy, is a common immune hypersensitivity disease that affects up to 40% of the population. Recently, the incidence of ocular allergies has increased, the symptoms of itching, redness and swelling significantly reduce patients’ quality of life. In this article the authors present a case report of a patient with isolated allergic conjunctivitis with negative results of commonly used allergy tests and additional diagnostic possibilities in the allergic conjunctivitis. Clinical signs of allergic conjunctivitis with negative results of skin prick tests and normal concentration of allergen-specific IgE in serum suggest to consider the diagnosis of an isolated allergic conjunctivitis. Isolated allergic conjunctivitis is a diagnostic and therapeutic challenge, both for ophthalmologists and allergists.