In this paper,a topology is presented for feasible workspace regions in general two-revolute manipulators.The design problem and concept of feasible workspace regions have been discussed as linked to each other.Design equations are formulated by arbitrarily prescribing four workspace boundary points.The so-called feasible workspace regions are the intersection of three different sub-regions,which are given by constraint curves as function of the relative positions of three workspace boundary points.By using a parametric study,all topologies for three sub-regions are figured out.Corresponding areas in cross section plane are determined for prescribing the position of a feasible workspace point as function of the topology for sub-regions.A classification has been proposed to determine and to characterize the combination of the topologies for those sub-regions.All topologies for feasible workspace regions are figured out and they are discussed as a design tool.Three general cases are analyzed in details to characterize workspace design capabilities for general two-revolute manipulators.