The aims of the present study were to investigate the antibacterial properties of glass-ionomer cements containing different concentrations of chlorhexidine and the possible release of chlorhexidine from the compound. Chlorhexidine gluconate or diacetate was mixed with glass-ionomer cements and tested in vitro against strains of Lactobacillus casei and mutans streptococci. A spectrophotometric test was used to monitor the release of chlorhexidine from the mixture. In a broth culture test, the higher the concentrations of chlorhexidine in the mixture, the longer the time of antibacterial effect on Streptococcus mutans and the greater the tendency of the material to deteriorate. Agar diffusion tests revealed bacterial inhibition in a dose-response manner. The tested bacterial strains were similarly inhibited and the antibacterial properties decreased with time. A minor portion of added chlorhexidine was released from the cement. The deterioration of the cements indicates that the material could be useful as a varnish-like chlorhexidine carrier.