Minimum essential medium supplemented with either 7% fetal bovine serum or 2% fetal bovine serum and 1.5% low protein serum replacement (Sigma Chemical Co., St. Louis, Mo.) factor was used to evaluate the growth of Vero 76 cells (E-6 clone) in a cell culture bioreactor. Three different microcarriers, collagen-coated polystyrene (Kontes Life Sciences Products, Vineland, N.J.), Gelibead (Hazelton Research Products, Inc., Lenexa, Kans.), and Cytodex 3 (Pharmacia Fine Chemicals, Piscataway, N.J.), were used to compare the propagation of these anchorage-dependent cells. The number of viable cells recovered during three harvests over an 11-day incubation period was evaluated. The Vero E-6 cells grew equally well with both media. When the collagen-coated dextran microcarriers (Cytodex 3) were used, better cell attachment and higher-density growth were obtained and 5.5 x 10(8) to 7.0 x 10(8) cells were recovered from the system.