All graphs in this paper are simple, finite, and undirected. The concept of rainbow coloring was introduced by Chartrand et al2. Let G be a non trivial connected graph. For k∈ℕ, we define a coloring c:E(G)→{1,2,…,k} of the edges of G such that the adjacent can be colored the same. A path P in G is a rainbow path if no two edges of P are colored the same. A path connecting two vertices u and u in G is called u−v path. A graph G is said rainbow-connected if for every two vertices u and u of G, there exist a rainbow u−v path. In this case, the coloring c is called the rainbow k-coloring of G. The minimum k such that G has rainbow k-coloring is called the rainbow connection number of G. Clearly that diam(G)≤rc(G) where diam(G) denotes the diameter of G. In this paper we determine the rainbow connection number of rocket graphs.