2-([(4-([Acetylamino]sulfonyl)phenyl)amino]carbonyl)benzoic acid (Phthalyl sulfacetamide) belongs to well known member of antimicrobial sulfonamide family. The lattice energy of molecular structure of Phthalyl sulfacetamide are calculated using simple atom-atom potential energy functions, using coulombic terms with point-charge parameters, and using the PIXEL formulation, which is based on integral sums over the molecular electron density to obtain coulombic, polarization, dispersion and repulsion lattice energies. To calculate the lattice energy of molecular pair, those are involved in intermolecular interactions established by X-ray data, are picked up. Protein-ligand interaction plays an important role in structural based drugs design. Docking studies are carried out on Phthalyl sulfacetamide to understand the structure function relationship. The selected receptors are docked with Phthalyl sulfacetamide and the interaction energy value obtained using GLIDE utility from Schrodinger software. The observation from docking results suggests that the Phthalyl sulfacetamide binds well with 4X45 having G-score value -10.19