ABSTRACT Diclofenac sodium is a lipophilic non-selective NSAID which has difficulties to penetrate due to its binding to high lipid content of stratum corneum. The addition of penetration enhancers in diclofenac sodium topical preparation needed to increase drug bioavailibility. Essential oil, such as ginger oil, is chemical penetration enhancer which considerably safe and has low irritation effect. This study was aimed to determine effect of ginger oil to preparation physical characterization, system stability, inflammatory effect, and irritation caused by application. Diclofenac sodium cream were made by varying ginger oil concentrations (1%, 3% and 5%). Another three formulas were also made to compare with preparation earlier stated, those were cream without ginger oil, 5% ginger oil cream without active ingredient, and cream without ginger oil and active ingredient. Physical characterization were observed on organoleptic, viscosity, spreadability, and adhesion time. System stability were observed on phase separation after centrifuged 10.000 rpm for 30 minutes. Antiinflammatory effect were evaluated on six groups of 5 male Wistar rats injected with 0.4 mL carrageenan 2% on left hind paw subplantar. Irritation test were determined using Primary Irritation Index. Data were analyzed statistically (α 0,05), except on organoleptic and system stability. Results showed ginger oil affect preparation organoleptic, viscosity, spreadability, and adhesion time. Cream were not experienced phase separation. Highest antiinflammatory effect were shown by 3% ginger oil cream. There were no irritation found on rats skin after application. Keywords: ginger oil, preparation physical characterization, system stability, antiinflammatory effect, irritation, chemical enhancer