Purpose.To investigate the efficacy of postoperative 5-fluorouracil (5-FU) in halting recurrence of pterygium.Methods.Early recurrence of pterygium was detected in six eyes of six patients aged 40 to 66 years that, over a 3-year period, had undergone pterygium excision in our institution, using the “bare sclera” technique. Each of the hyperemic fibrovascular tissues was found to override the cornea by 1.5 mm or less in length. Five of these eyes had undergone a primary excision and one, a second operation (with intraoperative mitomycin C). Upon diagnosis, each eye was treated with two to four injections of 5-FU, administered into the dome of the fibrovascular tissue. The dose of 5-FU per injection was 1 to 3 mg (mean, 2.1 ± 0.8 mg). Of all 126 eyes that underwent pterygium surgery during that 3-year period, pterygium recurred in nine additional eyes but was found to be 2 mm or more in length in each. These eyes were not treated by 5-FU.Results.In five of the six treated eyes, the pterygium became clinically atrophic and the recurrence process was stopped. No renewal of the recurrence process was detected after 12 months or more of follow-up. No major complications were related to the use of 5-FU.Conclusion.This pilot study suggests that when early recurrence of pterygium is already evident, 5-FU treatment into the dome of the fibrovascular tissue may be beneficial in halting its progression, by rendering it atrophic. A prospective, randomized, controlled study is required to confirm the efficacy of this approach.