Given a graph G = (V, E) with a label set L = { 1 , 2 , . . . , q }, in which each edge has a label from L, a source s ∈ V , and a sink t ∈ V , the Min Label s-t Cut problem asks to pick a set L ⊆ L of labels with minimized cardinality, such that the removal of all edges with labels in L from G disconnects s and t. This problem comes from many applications in real world, for example, information security and computer networks. In this paper, we study two linear programs for Min Label s-t Cut, proving that both of them have large integrality gaps, namely, Ω(m) and Ω(m 1/3− ) for the respective linear programs, where m is the number of edges in the graph and > 0 is any arbitrarily small constant. As Min Label s-t Cut is NP-hard and the linear programming technique is a main approach to design approximation algorithms, our results give negative answer to the hope that designs better approximation algorithms for Min Label s-t Cut that purely rely on linear programming.