In this study, a methacryloyl derivative of l-proline was synthesized, characterized and incorporated into a conventional glass ionomer cement (GIC) with a polyacid composition. Subsequently, the effects of incorporation of synthesized N-methacryloyl-proline and terpolymer on the GIC's mechanical and working properties were studied. 1-Methacryloylpyrrolidone-2-carboxylic acid was synthesized and used in a polymerization reaction with acrylic acid and itaconic acid in order to form terpolymer which was used in Fuji II commercial GIC formulations. Chemical structural characterization of the resulting products was performed using 1H nuclear magnetic resonance and Fourier transform infrared spectroscopy. The viscosity and molecular weight of the terpolymer were also measured. The mechanical strength properties of the modified GICs were evaluated after 24 h or 1 week of immersion in distilled water at 37 °C. Analysis of variance was used to study the statistical significance of the mechanical strengths and working properties, and to compare them with a control group. Results showed that N-methacryloyl-proline modified GICs exhibited significantly higher compressive strength (CS; 195-210 MPa), higher diametral tensile strength (DTS; 19-26 MPa) and higher biaxial flexural strength (38-46 MPa) in comparison to Fuji II GIC (161-166 MPa in CS, 12-14 MPa in DTS and 13-18 MPa in biaxial flexural strength). The working properties (setting and working time) of the modified samples showed that the modified cement was a fast-set cement. It was concluded that a novel amino acid-containing GIC has been developed in this study with 27%, 94% and 170% increases in values for compressive, diametral tensile and biaxial flexural strength, respectively, in comparison to commercial Fuji II GIC. © 2008 Acta Materialia Inc.