A new rehabilitation and fitness robot called the “Lambda Robot” is presented. This paper introduces a concept of a parallel robot that may be used for mobilization of the lower extremities. Hence, it may be used for fitness as well as for rehabilitation for people out of coma, after a surgical operation or for paraplegics. The kinematics and the construction aspects of the twice three degrees of freedom “Lambda robot” are presented. The different configurations it deals with are discussed to point out the advantages of this structure. Finally, the control and security aspects are presented. The constructed prototype is entirely instrumented with position and force sensors at each motorized articulation. This allows controlling all the movements and the corresponding generated forces.