BACKGROUND The therapy of malignant diseases of the conjunctiva with local chemotherapy is an extension of the therapeutic options in this field. We report on our experience in the therapy of malignant melanomas of the conjunctiva associated with primary acquired melanosis (PAM). METHODS AND PATIENTS Between March 1998 and April 2001, 13 patients with malignant melanoma of the conjunctiva associated with PAM (6 female; 7 male; mean age 57+/-13 years) were treated with local chemotherapy. The tumor was classified as stage pT2 (pN0, pM0) in seven patients, stage pT3 (pN0, pM0) in three patients and in the remaining three patients the lid was involved in the malignant process (pT4, pN0, pM0). Local chemotherapy (mitomycin C 0.02% eyedrops 5 times a day) was applied after incisional biopsies in 2 cycles for 14 days with a 14-day break. In 4 patients a third cycle was included. RESULTS Regression of the tumor was observed after completion of the therapy in all cases. Severe ocular or systemic secondary effects were not seen in our patients. Nine patients were without recurrence within the follow-up time. In three patients, a recurrence of the disease was observed. In these cases, the eyelid was involved in the process. CONCLUSION Local chemotherapy with mitomycin C is a useful option in the treatment of malignant melanomas of the conjunctiva associated with PAM if the tumor stage is pT3 or less. From our point of view the combination with incisional biopsy is of great benefit. Prognosis of conjunctival malignant melanomas involving the lid margin (pT4) is poor.