The synthesis of phosphorus containing dendrimers 2[G(0)]-2-[G(3)] and 3-[G(0)(")]-3-[G(1)(")] is achieved from the hexapodant N3P3(OC6H4CHO)(6)2-[G(0)] used as a core. It involves iterative reaction sequences : condensation reaction of 2[G(0)] with methylhydrazine followed by treatment of the resulting hydrazone with either chlorodiphenylphosphine or chlorodiazaphospholane, the last step being the reaction of the dendrimer possessing terminal aminophosphino groups with the azido thio phosphine N3P(S)(OC6H4CHO)(2) 4. The construction of the dendrimer of the third generation 2-[G(3)] is accomplished by reacting the arborol 2-[G(2)(")] possessing 24 phosphino groups at the periphery with 4. The same reactions conducted with the ligand (S)P(OC6H4CHO)(3) 6-[G(0)] used as a core,instead of 2-[G(0)], allow the preparation of dendrimers of the first, second, and third generation 6-[G(1)]-6-[G(3)(")].