In this note a new measure of irregularity of a graph G is introduced. It is named the total irregularity of a graph and is defined as irr_t(G) = 1 / 2∑_{u,v ∈V(G)} |d_G(u)-d_G(v)|, where d_G(u) denotes the degree of a vertex u ∈V(G). All graphs with maximal total irregularity are determined. It is also shown that among all trees of the same order the star has the maximal total irregularity.