To enhance the antibacterial activity of toxic drug compound sulfanilamide, it is doped by non-toxic compound 4-aminobenzoic acid by slow evaporation method. The powder XRD analysis shows that the doped crystal has both parent phases. The FT-IR and FT-Raman spectra of doped compound reveals the presence of functional groups of sulfanilamide and 4-aminobenzoic acid. The optical property of doped crystal is analyzed by UV-Vis-NIR spectroscopy. The morphology and elemental composition study confirms the presence of 4-aminobenzoic acid in the crystal lattice of sulfanilamide crystal. The antimicrobial activities of pure and doped crystals were tested against the five different micro-organisms by disc diffusion method. This result reveals that the doped crystal has more antibacterial activity than the pure sulfanilamide crystal.