| An efficient and systematic methodology for the topological synthesis of geared robot manipulators (GRMs) with a jointed unit is developed. The approach is based on the idea that the kinematic structure of a GRM with a jointed unit is composed of an equivalent open-loop chain (EOLC), disjointed mechanical transmission lines (MTLs), and jointed MTLs. It is shown that the jointed MTLs can be decomposed as a two-DoF nonfractionated jointed unit and several one-DoF disjointed units, connected in series. The characteristics of the jointed unit are laid out, and admissible jointed units are enumerated from the existing atlas accordingly. A systematic methodology is developed to enumerate admissible GRMs with a jointed unit of preferred DoF and number of links. It is also shown that the concept of jointed MTLs leads to the design of GRMs with decoupled joint motion by proper choices of gear ratios in the drive train.