The study of drug-drug interaction between Griseofulvin and Nortriptyline hydrochloride at binding sites of Bovine Serum Albumin (BSA) was studied by equilibrium dialysis (ED) method. During concurrent administration of these drugs, Griseofulvin (antifungal) and Nortriptyline hydrochloride (antidepressant) had been found to increase the respective free concentration of one another causing reduced binding to BSA. The increment in free concentration of was more prominent in presence of site-I specific probe (warfarin sodium) than in absence of it. The binding of Griseofulvin and Nortriptyline HCl was found to be enhanced to site-II (low affinity binding site) in presence of site-I specific probe. This modified form of displacement has tentatively been referred to as site-to-site displacement.