Quaternized copolymers of 4-vinylpyridine and poly(ethylene glycol) methyl ether methacrylate are known to have antibacterial properties and have displayed biocompatibility in red blood cell hemolysis assays. The results from hemolysis assays have shown substantial promise, but the technique is rudimentary and only a first step toward the determination of biocompatibility. The present paper further explores the biocompatibility of these copolymers through comprehensive cell viability assays performed on Caco-2 human epithelial cells cultivated in vitro. We have shown that these copolymers are biocompatible at concentrations above their minimum bactericidal concentrations, leading to selectivity values that compare well with other microbicidal products.