In the title compound, C(18)H(29)N(3)O, a polysubstituted guanidine, the torsion angles indicate that the guanidine unit and the carbonyl group are almost perpendicular to one another [O-C-N-C= -7.40 (18), C-N-C-N= -97.21 (15) and 86.41 (13)°]. The crystal packing is stablized by inter-molecular N-H⋯O hydrogen bonds, which link the mol-ecules into a chain.