Purpose: To determine the reliability and role of conjunctival exfoliative cytologic and histopathologic diagnosis of biopsied tissue in ocular surface squamous neoplasia. Design: Retrospective review of an interventional case series of patients biopsied and treated for squamous conjunctival and corneal neoplasia. Methods: Forty-nine patients who underwent conjunctival cytologic analysis (n = 36), conjunctival biopsy (n = 35), or both were evaluated. For the purposes of this study, three ocular pathologists reviewed the results of cytologic and biopsied tissue in a masked fashion. Results: Evaluation of cytologic smears revealed a 91% concordance in interpretation of conjunctival cytologic material as no dysplasia vs dysplasia. The concordance dropped to 59% in grading the degree of dysplasia. The cytologic material was found to be inadequate for interpretation in 1 case. Evaluation of subsequent biopsy revealed a 98% concordance between the pathologists in interpretation of biopsied tissue as no dysplasia vs any degree of dysplasia. The concordance decreased to 83% in grading the degree of dysplasia. Cytologic evaluation was capable of distinguishing a neoplastic from nonneoplastic process before tissue biopsy in 80% of cases. Conclusions: Ocular surface cytologic analysis is a simple, safe, and relatively noninvasive diagnostic tool. It was found helpful in detecting dysplasia before surgical resection. It was used in the settings of recurrent tumor and for follow-up care of patients treated with topical chemotherapy. Although cytologic smears cannot replace incisional or excisional biopsy for definitive diagnosis, exfoliative cytologic analysis can play an important role in the diagnosis and management of patients with ocular surface squamous neoplasia.