Wang “The Clinical Application and Research on Si Jun Zi Tang” It is the basic formula to treat Spleen Qi Deficiency. Many formulas have been developed that tonify Qi and invigorate the Spleen, but most evolved from the original Si Jun Zi Tang. The history, ingredients and Chinese herbal formulas derived from Si Jun Zi Tang will be reviewed in this article along with patterns of imbalance that this important Chinese herbal formula successfully treats.