Inflammatory cells infiltration after eugenol administration in Sprague Dawley rat's molars. The purpose of this study was to determine effect of eugenol on inflammatory cells infiltration (neutrophils, macrophages and lymphocytes) in the inflamed dental pulp. Thirty male Sprague Dawley rats aged 3-4 months and weighed 300-350 g were randomly divided into 2 groups: treated and control groups. Rats were injected with ketamine HCl i.m. (0.1 ml/100 grams BW) before cavity preparation at occlusal surface of the upper molars. Cavity preparation was made using a round bur No.010 to pulp perforation. At the cavity base of treated group, 15 rats were given eugenol and of control group 15 rats were given aquadest, before filled with temporary filling. Three rats from each group were sacrificed at 1, 3, 5, 7 and 14 days after the cavity preparation. Rats were injected with ketamine HCl im (0.1 ml / 100 g BW) on the thigh then tissues were collected for histological process and stained using haematoxylin eosin. The number of inflammatory cells (neutrophils, macrophages and lymphocytes) was analysed by Two-Way Anova. The result of the study showed number of inflammatory cells infiltration of treated group was lower than control and showed significant differences between groups (p <0.05). The conclusion from this study is eugenol administration in Sprague Dawley rats's inflamed dental pulp can reduce the number of inflammatory cells (neutrophils, macrophages and lymphocytes).