The responses of an osteoblast-like cell line to hydroxyapatite-zinc oxide-polyalkonate cement composites were investigated. The experiments demonstrated that zinc-based cements were cytotoxic in vitro under certain conditions. The setting of these cements involved neutralisation of acid groups on the water-soluble polyacrylic acids (PAA) by the base consisting of zinc oxide or a mixture of zinc oxide and hydroxyapatite (HA). It was found that as the HA content of the cements increased, an increase in the dissolution behaviour of the cements occurred.