Hand–foot syndrome (HFS) is a frequent dose-limiting adverse reaction of capecitabine in patient with gastrointestinal cancers. Silymarin is a polyphenolic flavonoid extracted from theSilybum marianumthat exhibits strong antioxidant and antiinflammatory activities. In this study, we evaluated silymarin efficacy in prevention of capecitabine-induced HFS in patients with gastrointestinal cancers, as the first human study. During this pilot, randomized, double-blinded, placebo-controlled clinical trial, the effect of silymarin gel 1%, which is applied on the palms and soles twice daily starting at the first day of chemotherapy for 9 weeks, on HFS occurrence was assessed. Forty patients fulfilled the inclusion criteria assigned to the silymarin or placebo group. World Health Organization HFS grading scale scores were recorded at baseline and every 3 weeks during these 9 weeks. The median WHO HFS scores were significantly lower in silymarin group at the end of the 9th week (p< 0.05). The scores increased significantly in both placebo and silymarin groups during chemotherapy, but there was a delay for HFS development and progression in silymarin group. Prophylactic administration of silymarin topical formulation could significantly reduce the severity of capecitabine-induced HFS and delays its occurrence in patients with gastrointestinal cancer after 9 weeks of application.