Hybridoma Supplement is a chemically defined growth-promoting supplement containing insulin, ethanolamine, hydrocortisone, retinoic acid, linoleic acid, and other growth-promoting factors. As a supplement to culture medium, it supports the growth of hybridoma in a manner that feeder cells have been used before. The disadvantages occurring by the use of feeder cells may include overgrowth of newly formed hybridomas, source of contamination, competition for nutrients, and variations in growth factor concentrations. Hybridoma Supplement can be used in culture medium under serum-free conditions. The low protein content facilitates the isolation and purification of produced antibodies. Hybridoma Supplement is provided as a 10x concentrate.