The synthesis, spectral characterization, crystal structure and antimicrobial activity of the novel synthetic molecule 7a-Aza-B-homostigmast-5-eno [7a,7-d] tetrazole, C₂₉H₄₈N₄ has been reported. The structure has also been determined by X-ray diffraction technique using direct method and was refined on F² by the full-matrix least-squares. Crystals are orthorhombic and their space group is P212121, with a=7.230(3), b=31.451(13), c=11.974(5)(Å), ⍺=β=γ=90°. It can be conveniently obtained by the reaction of 7-Oxostigmast-5-ene with hydrazoic acid. The molecule has also been screened for its possible in vitro antimicrobial activity against Staphylococcus aureus, Streptococcus mutans, Streptococcus pyogenes, Staphylococcus epidermidis, Bacillus cereus, Corynebacterium xerosis, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas aeruginosa (MTCC 424). Minimum inhibitory concentration (MIC) of the synthesized compound has also been evaluated. The highest activity is observed against C. xerosi and P. vulgaris. Moreover, the compound has also been screened for its in vitro cytotoxicity against human colon carcinoma cell line, HCT116 and human liver hepatocellular carcinoma cell line, HepG2, using doxorubicin as standard. On the basis of its IC₅₀ values, 7a-Aza-B-homostigmast-5-eno [7a,7-d] tetrazole was found to inhibit the cancer cells effectively.