Motivated by the Channel Assignment Problem, we study radio k-labelings of graphs. A radio k-labeling of a connected graph G is an assignment c of non negative integers to the vertices of G such thatfor any two vertices x and y, x = y, where d(x, y) is the distance between x and y in G.In this paper, we study radio k-labelings of distance graphs, i.e., graphs with the set Z of integers as vertex set and in which two distinct vertices i, j ∈ Z are adjacent if and only if |i − j| ∈ D. We give some lower and upper bounds for radio k-labelings of distance graphs with distance sets D(1, 2, . . . , t), D(1, t) and D(t − 1, t) for any positive integer t > 1.