Abstract. For a connected graph G of order n and minimum degree δ we prove the existence of two disjoint dominating sets D 1 and D 2 such that, if δ ≥ 2, then |D 1 ∪D 2 | ≤ 6 7 n unless G = C 4 , and, if δ ≥ 5, thenn. While for the first estimate there are exactly six extremal graphs which are all of order 7, the second estimate is asymptotically best-possible.