OBJECTIVE To discuss possible factors that could influence the prognosis of primary malignant conjunctival tumors. METHODS We retrospectively analyzed medical records of 79 patients followed for primary malignant conjunctival tumors between January 1997 and July 2011. RESULTS The mean age at the time of diagnosis was 61.1 years; male/female ratio was 2.59. The mean tumor size was 13.9 mm. The histological type was invasive squamous cell carcinoma in 43 cases (54.4%), epithelial dysplasia in 11 cases (13.9%), carcinoma in situ in 7 cases, conjunctival malignant melanoma in 5 cases, conjunctival lymphoma in 4 cases and other rare tumors in 9 cases. We performed an excisional biopsy with a safety margin in 89.8% of cases, associated with cryotherapy in 46.6% of cases. Enucleation was performed in two cases and orbital exenteration in 5 cases. We noted tumor recurrence in 33.3% of patients after an average period of 9.5 months. Radiation therapy was indicated in 44 cases (55.7%). The mean follow-up of our patients was 42 months. Tumor recurrences were statistically associated with a history of xeroderma pigmentosum (P=0.012), a diagnostic delay more than 11 months (P=0.001), caruncular location (P=0.004), tumor size greater than 10mm (P=0.044), scleral extension (P=0.011), initial treatment limited to excisional biopsy (P=0.033) and histopathologic involvement of the margin of the tumor resection (P=0.008). CONCLUSIONS A better understanding of the prognostic factors of primary malignant conjunctival tumors is essential for management and may improve the prognosis of these tumors.