The characteristic feature of ocular cicatricial pemphigoid (OCP) is progressive shrinkage of the conjunctiva. In our series of 78 patients with OCP, 21% had cutaneous involvement and 50% had involvement of the oral mucosa. Immunoglobulins and the third component of complement are found bound to the conjunctival epithelium and basement membrane of patients with OCP. Circulating antibodies which bind to the conjunctival and corneal epithelium but not to the conjunctival basement membrane have also been demonstrated. OCP is associated with an increased prevalence of HLA-B12. The lids and conjunctiva of patients with OCP demonstrate an increased incidence of potential pathogens when compared with age- and sex-matched controls. When followed for a period averaging 22 months, the majority of patients not treated with systemic immunosuppressives or topical corticosteroids progress. However, OCP has a variable course because there were patients in all stages who did not progress. The acute manifestations of OCP may cause rapid shrinkage of the conjunctiva and may be suppressed with systemic corticosteroids.