We are interested in the homogenization of a stationary Bingham flow in a porous medium. The model and the formal expansion of this problem are introduced in Lions and Sanchez-Palencia (J. Math. Pures Appl. 60:341–360, 1981) and a rigorous justification of the convergence of the homogenization process is given in Bourgeat and Mikelic (J. Math. Pures Appl. 72:405–414, 1993), by using monotonicity methods coupled with the two-scale convergence method. In order to get the homogenized problem, we apply here the unfolding method in homogenization, method introduced in Cioranescu et al. (SIAM J. Math. Anal.40:1585–1620, 2008).