Keratoconjunctivitis sicca (KCS) is one of the dry eye syndromes characterized by a deficiency of the aqueous layer of the tear film. The disorder may occur as an isolated entity or in association with a variety of local and systemic conditions affecting aqueous production. Often it follows a mild course but in severe cases, complications resulting in blindness may occur. In this paper, the clinical features, diagnostic strategies, and current treatment of KCS will be covered. Etiologies, including a discussion of the Sjögren syndrome, will also be presented.