microRNAs (miRNAs) are nowadays recognized as an essential component of gene regulatory networks. Furthermore, deregulation of miRNAs expression often contributes to human pathologies. Recently, a substantial number of single nucleotide polymorphism (SNPs) and rare mutations within pri-, pre- and mature miRNA sequences have been reported. These miRNA SNPs have often been associated with human disease. However, due to the complexity of miRNA biogenesis and the genome-wide functional effects of miRNAs, the determination of biological consequences of these miRNA SNPs remains challenging. Despite an increasing number of reports linking miRNA SNPs with human pathologies, few reports have analyzed the mechanism by which miRNA-SNPs contribute to disease pathogenesis. In this review, we discuss how single polynucleotide polymorphisms in miRNAs genes may influence miRNAs expression and function and thus potentially alter disease pathogenesis.