Background. Keloids and hypertrophic scars are fibroproliferative disorders of dermal tissue after skin injury. Many clinical control studies have reported evidence that silicone gel is effective in preventing and alleviating hypertrophic scarring. Whether silicone gel sheeting prevents hypertrophic scars or keloids requires clear evidence of its clinical effectiveness.Objective. This review investigated the effectiveness of silicone gel and silicone gel sheeting for the prevention of hypertrophic or keloid scarring in patients with newly healed wounds. Methods. The authors searched the MEDLINE, EMBASE, CINAHL, and CENTRAL databases (January 1, 1990 to September 24, 2014) for any randomized or quasi-randomized controlled trials or controlled clinical trials comparing silicone gel sheeting or silicone gel with a control group for prevention of hypertrophic scars or keloids. All collected trials were assessed for methodological quality, control group and treatment group, and number of participants developing hypertrophic scars and keloids. The authors calculated risk ratios (RR) from each trial for the development of abnormal scarring and combined these using random-effects model meta-analysis. Between-study heterogeneity was calculated by using the I2 statistic. Results. Ten trials in 9 studies were pooled (random effect; I² = 88%). There was a significant difference between the silicone gel sheeting group and the placebo group (RR 0.70; 95% confidence interval, 0.49–0.99; P = .04) in preventing the risk of hypertrophic scars. Conclusion. There was statistical significance in the effectiveness of silicone gel and silicone gel sheeting on the prevention of keloids or hypertrophic scars, especially in skin lesion wounds. However, most of the trials evaluating silicone gel sheeting or silicone gel as a prevention of hypertrophic scars and keloids had poor quality with high or uncertain risk of biases either in study design or in conduct.