This study was performed to determine the subacute toxicities of SKI306X, an antiinflammatory herbal extract, in rats. SKI306X was administered orally to rats once a day for 4 weeks at doses of 0.3, 1.0, and 3.0 g/kg/ day. Each group consisted of 20 male and 20 female rats, including 5 male and 5 female rats per group for an interim study at the end of 2-week administration and for a 2-week recovery study, respectively. Throughout the study, all rats survived and no adverse clinical signs were observed. Although male rats treated with high dose (3.0 g/kg/day) of SKI306X showed slight loss of body weight (approximately 5%) in comparison with control animals during the administration period, their body weight loss was normally restored during the recovery period. No significant change was found in all hematological parameters of SKI306X-treated groups except for the decreased number of red blood cells in all female groups at the interim study. Statistically significant changes were observed in several blood enzyme levels of SKI306X-treated groups; however, most of these significant changes were within normal range and statistically significant values did not show dose-related responses. In SKI306X-treated groups, the absolute and relative weights of liver, heart, and stomach were statistically different from those of control group, but these differences disappeared at the end of recovery period and also drug-related gross and histopathological findings in these organs were not found. No other drug-related gross and histopathological findings were observed. It is concluded from the results of this study that non-toxic dose of SKI306X was estimated to be between 0.3 and 1.0 g/kg/day and the maximum tolerated dose of SKI306X was assumed to be higher than 3.0 g/kg/day.