Several groups have developed robotic systems for invasive medical procedures. In this article we will focus on selected robotic systems for percutaneous needle-guided interventions using CT or MR imaging. We present six interventional robotic systems designed to work with imaging modalities such as CT, Cone-beam CT and MRI. The details of each system are given along with any phantom, animal, or human trials performed with each particular robot. Although each of these systems has specific features, they are all of great clinical value since they provide very stable needle guidance -- even for angulated approaches, they may allow access to lesions when the width of the CT- or MR- gantry would limit the access for a biopsy needle or other interventional tools such as thermal ablation probes. Then, such a robot may be able to guide the needle into the most promising region of the lesion without the need for a second contrast injection. Thus, more efficacious characterization and treatment, particularly for lesions that are difficult to target, can be anticipated. Although more research and clinical trials are certainly needed, it is, however, our belief that robotic systems will be an important part of future interventions.