Abstract: A serum free cell culture medium containing less than 10 ug/ml protein is disclosed. The medium comprises a basal media supplemented with levels of 2-aminoethanol substantially higher than previously disclosed and supplemented with 2-mercaptoethanol, transferrin, insulin and free essential amino acids. Unlike other serum free media, the media disclosed herein will support the growth and long term culture of a large variety of cell types including hybridomas and tumor cell lines while maintaining both growth potential and the differentiated characteristics of the particular cell line.