The growth of animal cells cultures takes place in a complex medium for cultivation which is composed of nutrients such as salts, amino acids, vitamins, glucose and serum supplement. Serum is the most expensive component of the medium for the cultivation of animal cells and among others contains components which are not always chemically characterised. Because serum is the most expensive component of the medium, interest in development of media without the addition of serum stimulate is increasing. Serum could be replaced with protein hydrolysates derived from animal tissue, milk, yeast or plants. Protein hydrolysates are obtained by enzymatic, microbial or acid hydrolysis of biological material which contains a variety of nutrients, such as amino acids, oligopeptides, lipids, trace elements, vitamins and minerals and other compounds that stimulate the proliferation and influence the increased activity of cells. The aim of this study was to investigate the influence of addition of protein hydrolysates of yeast, wheat gluten and soy on the proliferation of cell lines CCO in UC medium without serum. Examining the influence of addition of these hydrolysed proteins at a concentration of 4 g L-1 is found that the biggest impact on growth of the CCO cells had wheat gluten hydrolysate. The concentrations (8 and 12 g L-1) had an inhibitory effect on the growth of the CCO cells. Adding fraction of wheat gluten hydrolysates of 5 and 10 kDa, had a stimulating effect on the growth of the CCO cells. The combination of wheat gluten and soy hydrolysates (1+3 g L-1) showed the best effect on the proliferation of the CCO cells. Further research should examine the possible stimulating influence of other plant hydrolysates on CCO cell proliferation and mechanisms of their action.