The reactions of phosphorus trichloride with three molar equivalents of methylamine and ethylamine give bis-(dichlarophosphino)amines (Cl2P)2NR (R = Me and Et), and with isopropylamine and t-butylamine, cyclodi-phosph(III)azans, (ClPNR)2(R = PrI and But) are obtained as major products. There is mass spectroscopic evidence for the cyclophosph(III)azans, (ClPNEt)n(n= 2 or 3) in the products from the reaction with ethylamine, but these compounds have not been obtained pure. Several other potential routes to N-methylcydophosph(III)azanes were examined, inculding the reaction of phosphorus trichloride or of bis(dichlorophosphino)methylamine, (Cl2P)2NMe, with heptamethyldisilazane, (Me3Si)2NMe, which gave the dichiorophosphinamines, Cl2P·NMe·SiMe3(Cl2P)2NMe, and the cage compound P4(NMe)6, but no compounds of the type (ClPNMe)nwere obtained. Similarly, dichloroaiylphosphines and hepiamcthyldisilazane gave the phosphinamines ClArP·NMe·SiMe3 and (ClArP)2NMe (Ar = Ph or C6H4-p-Me). m-Chtoroaniline hydrochloride reacts with phosphorus trichloride affording (Cl2P)2NC6H4-m-Cl, which with SbF3produces (F2P)2NC6H4-m-Cl. (Cl2P)2NPh and the analogous fluoride were obtained similarly. The cyclodiphosph(III)azanes, (ClPNR)2(R = PrI or But), gave monoxides and monsulphides containing PIII and PV atoms within the ring system, on reaction with dimethyl sulphoxide and elemental sulphur respectively. Oxothioxocyclodiphosphazanes were obtained by a related route. The 1H and 31P n.m.r. spectra of these compounds are reported and discussed.