This is the final step in preparing injectable constructs for RNA interference. This protocol starts with a 20 uL T7-polymerase transcription reaction. We use New England Biolab's HiScribe kit. Our template cDNA has been prepared with T7 promoter regions at each 5' end, enabling RNA transcription in both directions. After dsRNA has been extracted, pelleted, and resuspended in pure nuclease-free water, we will melt the strands apart and allow them to reanneal slowly to ensure that we have plenty of properly double-stranded RNA. The protocol is based on the manufacturer's manual for the HiScribe kit, modified with information from the MegaScript T7 RNA transcription kit manual (Ambion).