Ocular allergy is a common condition that usually affects the conjunctiva of the eye and is therefore often referred to as allergic conjunctivitis. The severity of the disease can range from mild itching and redness, as seen in seasonal allergic conjunctivitis, to the more serious vision threatening forms of ocular allergy which affect the cornea, such as atopic keratoconjunctivitis. The pathogenesis of allergic conjunctivitis involves a complex mechanism which centers around IgE-mediated mast cell degranulation and release of multiple preformed and newly formed inflammatory mediators. The diagnosis of allergic conjunctivitis is usually a clinical one which can be made based on a thorough history and careful examination. Treatment of ocular allergy should begin with conservative measures including allergen avoidance, environmental control, ocular irrigation and cold compresses. Pharmacotherapy of allergic conjunctivitis consists of several classes of drugs. Antihistamines are widely used to treat mild conditions such as seasonal and perennial conjunctivitis and potent new agents such as levocabastine and emedastine are now available. Mast cell stabilizers such as sodium cromoglycate are both safe and effective and are commonly used in ocular allergy. More effective mast cell stabilizers such as nedocromil, lodoxamide and olopatadine are now being used. Nonsteroidal antiinflammatory drugs have demonstrated only limited efficacy and, as such, are not widely used. Topical steroids are very effective in treating signs and symptoms but are reserved for only refractory cases due to their serious side effects. Loteprednol and rimexelone are newer corticosteroids which reportedly have less of an effect on intraocular pressure. Cyclosporine has recently been shown to be highly effective in cases of vernal keratoconjunctivitis and atopic keratoconjunctivitis while producing no adverse effects.