A proprietary, oral Chinese medicinal herb preparation with potential antioxidant, immunomodulating, and antineoplastic activities. THL-P (Tien-Hsien Liquid-P) contains fourteen Chinese medicinal herbs including: Cordyceps sinensis, Oldenlandia diffusa, Indigo pulverata levis, Polyporus umbellatus, Radix astragali, Panax ginseng, Solanum nigrum L., Pogostemon cablin, Atractylodis macrocephalae rhizoma, Trichosanthes radix, Clematis radix, Margarite, Ligustrum lucidum Ait and Glycyrrhiza radix. Administered as an oral liquid, THL-P may modulate the activity of natural killer (NK) cells, cytotoxic T-lymphocytes (CTLs), macrophages and polymorphonuclear leukocytes, and enhance the secretion of interleukins (ILs) and interferon-gamma (IFN-gamma). This agent may also induce G2/M cell cycle arrest and downregulate several important oncogenic signaling pathways.