The invention relates to compositions suitable for plasma substitution comprising as a plasma expander a recombinant gelatin-like protein. Characteristic is that the gelatin-like protein essentially is free of hydroxyproline. This absence of hydroxyproline prevents the composition from gelling and thus allows the use of high-molecular weight proteins in order to establish a suitable colloid osmotic pressure. Specific advantage of the gelatin-like proteins is that these avoid the risk of anaphylactic shock that exists in conjunction with the use of commercially available preparations.