We prove that the 8(2)(4) link complement is the minimal volume orientable hyperbolic manifold with 4 cusps. Its volume is twice the volume V-8 of the ideal regular octahedron; that is, 7.32 ... = 2V(8). The proof relies on Agol's argument used to determine the minimal volume hyperbolic 3-manifolds with 2 cusps. We also need to estimate the volume of a hyperbolic 3-manifold with totally geodesic boundary which contains an essential surface with non-separating boundary.