As serum elimination from animal cell culture media aims at avoiding the risks associated with components of bovine origin, additives such as protein hydrolysates from plant sources are proposed. In this study, we evaluate the interest of adding various peptide mixtures, obtained by membrane fractionation of an enzymatic hydrolysate of rapeseed proteins, in CHO cell cultures. While the total hydrolysate and some fractions derived from this hydrolysate do not affect CHO cell kinetics, one fraction, composed of a mixture of both large (500-5000 Da) and small peptides (< 500 Da), significantly stimulates cell growth rate (maximal cell density x 1.7) when added at 4 g/l. In addition, this fraction allows the formulation of a safe, very simple protein-free medium (RPMI + rapeseed peptides), which does not compromise cell growth in stirred conditions, strongly reduces cell death rate (culture duration time x 2), increases recombinant gamma-interferon production, accelerates cell adaptation to serum-free conditions and facilitates cell cryopreservation. (c) 2006 Elsevier Ltd. All rights reserved.