Let G = (V, E) be a graph. An injective function f:V→N is said to be a k-Zumkeller labeling of the graph G if the induced function f*:E→N defined by f*(xy)=f(x)f(y) satisfies the following conditions(i)For every xy∈E, f*(xy) is a Zumkeller number.(ii)|f*(E)|=k, where |f*(E)| denotes the number of distinct Zumkeller numbers on the edges of the graph G. In this paper we prove that twig graphs admit a 4-Zumkeller labeling. © 2015 Elsevier B.V.