The crystal structures of three (N-phenylthioureidoalkyl- and -aryl)phosphonates, i.e. diphenyl [(3-phenylthioureido)phenylpropyl]phosphonate, diphenyl [1-(3-phenylthioureido)benzyl]phosphonate and diphenyl [2,2-dimethyl-1-(3-phenylthioureido)propyl]phosphonate, have been determined by X-ray diffraction. The conformations of the title molecules, the geometry of the thioureide fragments and molecular packing arrangements are analyzed and compared with literature data.