Abstract: The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most polyphagous herbivores, feeding on cell contents of over 1100 plant species including more than 150 crops. T. urticae is one of the major pests for greenhouse and horticultural crops, including tomatoes, cucumbers, roses, strawberries and hops, and many field crops, such as cotton, corn and soybean. This arthropod is found world-wide, particularly in regions with a warm, dry climate. Despite efforts to control T. urticae by using pesticides, this pest remains a serious problem in agriculture. The availability of the spider mite genome, in combination with transcriptome and proteome databases, has greatly advanced our understanding of spider mite biology. Recently, RNA interference (RNAi) technology was developed as an attractive alternative for the control of insect pests. RNAi is based on sequence-specific gene silencing that is triggered by the presence of double-stranded RNA (dsRNA). This technology has been widely used as a reverse genetics approach to study gene function in arthropods and other organisms where alternative approaches for genetic manipulation are not available or practical. Our aim in this review is to focus on current knowledge of RNA interference in arthropods and more specifically, in T. urticae.