A new microcarrier (MC) culturing system for anchorage-dependent cells is described. The system is based on polyacrylein microspheres encapsulated in agarose and derivatized by various amino ligands. In practice, any protein or ligand with primary amino groups may be covalently bound to the microspheres through their aldehyde groups. The ease with which the beads may be derivatized enables the preparation of MC with desired surface properties for growing a variety of cells. In this model system the beads were derivatized by 2-(diethylamino)ethylamine (DEAE), diaminohexane (DAH), poly-L-lysine (PL), gelatin and collagen. The derivatized beads supported the growth of primary cells, diploid cell strains and established cell lines for biological studies as well as for production of various cell products.