Objective: To demonstrate that conjunctival impression cytologic analysis can detect conjunctival intraepithelial invasion from sebaceous cell carcinoma of the eyelid. Design: Observational case series with cytopathologic correlation. Participants. Four patients with unilateral blepharoconjunctivitis and biopsy-proven sebaceous cell carcinoma. Methods: Impression cytologic analysis specimens were taken from the suspicious area of the bulbar conjunctiva of each patient. Staining of the specimens was performed with a modified Papanicolaou stain. Main Outcome Measure: Observation of the abnormal tumor cells in the collected specimens by bright field microscope. Results: The technique of impression cytologic analysis allowed collection and identification of abnormal tumor cells with characteristic cytoplasmic vacuoles. Conclusions: Conjunctival impression cytologic analysis successfully detected the ocular surface sebaceous carcinoma cells from the eyelid. However, full-thickness biopsies are necessary to confirm the diagnosis. Judicious use of impression cytologic analysis may facilitate the detection and diagnosis of this invasive tumor.