An efficacious vaccine adjuvant which elicits both cell-mediated immunity (CMI) and humoral immune response was developed using [thr1]-Muramyldipeptide (MDP) in an oil-in-water emulsion vehicle containing poloxamer 401, polysorbate 80, and squalane. Processing optimization was performed to increase the physical stability of this adjuvant emulsion which, when prepared by conventional mixing methods, demonstrated good bioactivity but poor physical stability. Various manufacturing methods were compared with a microfluidization process, which produced the most stable and elegant emulsion vehicle. The microfluidized emulsion also elicited equivalent biological response in the animal model tested.