A k-sun graph S(Ck) is a graph obtained from a k-cycle by adding a pendent edge to each vertex of the k-cycle. A k-sun system of order v is a decomposition of the complete graph Kv into k-sun graphs. In this paper, we find the necessary and sufficient condition for the existence of a 5-sun system of order v. Moreover, we obtain cyclic 5-sun systems when View the MathML source and 1-rotational 5-sun systems when View the MathML source.