Keloids are aesthetically disfiguring and severely disabling. The optimal treatment remains undefined. This clinical study, evaluate the efficacy and side effects of combined topical silicone and 5-Fluorouracil on the prevention of keloids. In this double blind randomized clinical trial, fifty patients with keloids were randomly allocated in two groups. The control group were treated by perilesional surgical excision of keloids combined with topical silicone and the trial group were treated with adjuvant treatment of intralesional 5-Fluorouracil. All patients were examined and assessment was done by an independent observer. the data collected were analyzed by SPSS statistical software with using tables and χ square tests. 75% of the cases in the trial group were keloid free 21% have keloid partially improvement and 4% have keloid recurrence, compared to patients in the control group respectively: 43%, 35% and 22%, findings suggest that efficacy of 5-Fluorouracil combined with topical silicone used for the prevention of keloid is comparable to other modality. The lack of any serious side effects and the evidence of recurrence at one year of follow-up make this an effective tool for the prevention of keloids.