This work involves synthesis of different five, six and seven membered heterocyclic rings starting from Malonic acid dihydrazide which was synthesized from the corresponding diethyl malonate on its reaction with hydrazine hydrate. This work is divided into four different parts: First part: This part involved the synthesis of oxadiazole[9], triazole[3,19,22], thiadiazole[11,18] , thiadiazine[4], , pyridazin-3,6-dione [5] ,phthalazin -3,8-dione[6] and pyrazole[7,8] from compounds [a], [1] with different organic materials as shown in Schemes (I). Second part: This part involved the synthesis of thiosemicarbazide[16], semicarbazide[20],Thiazolidine[17] and Oxazoline[21]derivatives from malonic acid dihydrazide [1], as shown in Scheme (III). Third part: This part involved the synthesis of two new Schiff bases[12,14]derived from malonic acid dihydrazide [1] with two aromatic aldehydes and cyclization by the treatment with phthalic anhydride resulted oxazepines [13, 15] as shown in Scheme (II).