This study represents the first comprehensive investigation examining the effects of polymorphisms in CYP3A4*1B (c.-392G>A, rs2740574), CYP3A4*22 (c.522-191C>T, rs35599367), CYP3A5*3 (c.6986A>G, rs776746), UGT2B7 (rs73823859, rs7439366, and rs7668282), and ABCB1 (rs4148738, rs1045642, rs2032582, and rs1128503) on both the pharmacokinetics and clinical effects of silodosin in BPH patients. Here, CYP3A4 is linked to benign prostatic hyperplasia.