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Most research on the thumb kinematics has focused on the local trapezo-metacarpal movement independently of the hand. In the clinical area, these studies can be sufficient. However, when the simulation of the hand movement and prehensile tasks with numerical dummies is needed, the thumb has to be considered as an integral part of the hand so a study in this direction proves to be essential. The objective of the present study is to analyze the kinematics of the thumb in relation to the hand (i.e. from the wrist’s joint). This paper proposes a four-link kinematic model of the thumb with 5 degrees of freedom (DOF) for a better representation of the opposition of the thumb with the other fingers. The interphalangeal and the metacarpophalangeal joints of the thumb have 1 flexion/extension DOF each and the carpo-metacarpophalangeal has 3 DOF (flexion/extension, abduction/adduction and rotation).