In this present study, we determined the immunoregulatory activity of ginsenoside Rd extract from Panax ginseng. To determine the activity, we tested Rd against $CD4^+$ Th cells in a murine model of type 1 diabetes, which involves Th1-dominant immunity. The type 1 diabetes was caused by streptozotocin (STZ) and the severity of the diabetes was evaluated by measuring the degree of hyperglycemia, a major symptom of diabetes. The data resulting from experiments showed that ginsenoside Rd induced a greater level of Th1 type cytokines [IFN-${gamma}$ & IL-2] than Th2 type [IL-4 & IL-10] (P<0.05), which was determined by cytokine profile analysis. In the animal model of diabetes, the depletion of $CD4^+$ Th cells by a treatment of anti-CD4 mAb resulted in considerably lower values of blood-glucose levels than those of the mAb-untreated mice, which indicates that the Th1 immune response from $CD4^+$ Th cells are responsible for diabetes. Based on these observations, the effect of Rd on diabetes was examined in the same animal model. Results showed that Rd-treated mice groups had increased levels of blood glucose compared to Rd-untreated mice groups that were used as a negative control (P<0.05). In other words, Rd aggravated the diabetes via the Th1 immune response. In conclusion, ginsenoside Rd had an immunoregulatory activity of Th1-dominant immunity.