This report describes the development of a robotic assistance system that provides precise and reproducible instrument positioning inside the MRI or CT gantry on the basis of processed imagery. Percutaneous interventions such as MRI-guided insertion of cannulae and probes for biopsy, drainage, drug delivery, and energetic tumor destruction were primary drivers in the robotic design. Applications involving the central nervous system have been excluded because of the demanding medical device regulations and approval process. The developed system received the Conformite Europeenne (CE) mark in 2005 and is marketed under the brand name INNOMOTION. It is currently in clinical use for MRl-guided sciatic pain and facet joint treatments, biopsies,drainages, and CT-guided osteosynthesis. This article reviews the development and evaluation of the system.