The new pyrazolo[4,3-e][1,3,4]oxadiazine heterocyclic ring system was prepared and employed to synthesize cyanine dyes of different methine types, (mono, tri, penta and hepta). The antibacterial activity of all the newly synthesized compounds was investigated against some bacterial strains. The electronic absorption spectra of the dyes were also studied in ethanol. The structure of all the synthesized compounds was identified via elemental and spectroscopic analysis.