We studied the recurrence rate of pterygium after administration of a single dosage of topical mitomycin C at the completion of pterygium surgery. Forty patients who had advanced or recurrent pterygium underwent excision of pterygium, leaving the sclera bare. Patients were randomized in a masked fashion into two groups of 20 patients each. Group 1 received a single dosage of topical 0.02% mitomycin C for 5 min at the completion of the surgery whereas group 2 underwent the same procedure but received NaCl 0.9% instead of mitomycin C. Patients were followed from 6 to 15 months in a masked manner. The pterygium recurred in one patients (5%) in group 1, whereas in group 2 the recurrence rate was 45% (p = 0.0035). Formation of dellen and a delay of epithelialization for 5 weeks were found in one patient in group 2. No complications were observed in patients in group 1. This study indicates the possible advantage of administration of a single dosage of 0.02% mitomycin C for postoperative prevention of recurrence of pterygium.