AIMS: To demonstrate the efficacy of mitomycin C as adjuvant therapy preoperatively and intraoperatively in the management of recurrent or diffuse ocular surface neoplasias. METHODS: The case notes of 11 patients receiving mitomycin C adjuvant therapy as 0.04% eye drops four times a day in two weekly courses preoperatively and/or a single intraoperative application of 0.4 mg/ml of mitomycin C were reviewed. The histopathology included conjunctival primary acquired melanosis, conjunctival melanomas, sebaceous cell carcinomas with conjunctival intraepithelial spread, and conjunctival intraepithelial squamous neoplasias. Seven patients had additional limited local excision of the residual tumour mass and one had cryotherapy. RESULTS: All cases showed a favourable response to mitomycin C adjuvant therapy with regression in size or retardation of a rapid growth pattern and no serious sequelae. Postoperative follow up of 6-36 months following excision of the lesion with or without intraoperative mitomycin C showed no clinical recurrence in any of the cases. CONCLUSION: In this series, mitomycin C adjuvant therapy of recurrent or diffuse ocular surface neoplasias was well tolerated and showed favourable clinical results.