In children, MR arthrography is typically performed using fluoroscopic guidance. This article explores the role of US-guided joint injections as an alternative for MR arthrography in children, discussing its advantages and disadvantages compared to standard methods. We describe techniques for performing US-guided injection of the shoulder, elbow, hip, knee, ankle and posterior subtalar joints, highlighting pertinent anatomy, routes of access and unique considerations for this modality in children. Written descriptions, images and links to video clips are used to illustrate proper arthrographic technique. We conclude that US provides effective guidance for intra-articular injection prior to MR arthrography, with the advantages of improved visualization of internal structures, reduced radiation exposure, convenience of performing the procedure portably and ease of performance. Although this paper does not address therapeutic steroid injections, these techniques could easily be translated for such purposes. We propose US guidance as a viable alternative to fluoroscopic technique for arthrography in children.