The title compound, C(21)H(22)NO(3)P, was synthesized from the reaction of (C(6)H(5)O)(2)P(O)(Cl) and S-1-phenyl-propyl-amine (1:2 mole ratio) at 273 K, followed by removal of the S-1-phenyl-propyl-amine hydro-chloride by-product by dissolving in H(2)O. The P atom is located in a distorted tetra-hedral environment. The bond angles at the P atom vary from 99.51 (12) to 116.68 (12)°. The sp(2) character of the N atom is reflected by the C-N-P angle [120.9 (2)°]. The P=O group and the N-H unit adopt an anti orientation with respect to one another. In the crystal, adjacent mol-ecules are linked via N-H⋯O(P) hydrogen bonds into a one-dimensional arrangement running parallel to the a axis.