CHO serum-free basal medium is a fully chemically-defined (CD) basal medium free of hydrolysates, proteins, growth factors, and any animal-derived components. It is suitable for high-density suspension culture of various Chinese hamster ovary cell subtypes (CHO-K1, CHO DG44, CHOZN, etc.). When used with high-performance supplements (CHO Serum-Free Supplement A, CHO Serum-Free Supplement B), this medium supports high-density cell growth and viability maintenance, enabling higher levels of protein/antibody expression and quality.