  In this paper we give a proof of an epiperimetric inequality in the setting
of the lower dimensional obstacle problem. The inequality was introduced by
Weiss (Invent. Math., 138 (1999), no. 1, 23-50) for the classical obstacle
problem and has striking consequences concerning the regularity of the
free-boundary. Our proof follows the approach of Focardi and Spadaro (Adv.
Differential Equations 21 (2015), no 1-2, 153-200.) which uses an homogeneity
approach and a {\Gamma}-convergence analysis.
