Purpose: To understand the effect of the addition of hydroxyapatite (HA) and bioactive glass (BAG) to compomer restorative materials on the remineralisation capacity of the material. Materials and Methods: 1%, 2%, 3% and 4% w/w HA and BAG particles were added mechanically to the compomers. To examine the resistance to demineralisation, Class V cavities were prepared in extracted teeth and restored with experimental filling materials. Demineralised lesions were created in 72 enamel samples. Vickers microhardness measurements of samples were performed at three different areas including the margin of the restoration, the varnish-protected enamel and the exposed enamel areas. Measurements performed on protected enamel were used as reference enamel values for each group. SEM was used to evaluate the surface texture of the specimens. The statistical analyses were performed by one-way ANOVA, Tukey's HDS and paired-samples t-tests. Results: BAG and HA groups revealed higher microhardness values at the exposed enamel and exposed marginal enamel than did the control group (p = 0.001). 3% and 4% HA and BAG groups produced higher microhardness values than did 1% modified groups on exposed enamel (p = 0.001). 4% HA group revealed the highest microhardness values on marginal exposed enamel (p = 0.001). 2%, 3%, 4% and HA, as well as 3% and 4% BAG groups showed higher microhardness values than did the control group on marginal exposed enamel at 20 µm depth (p = 0.001). SEM images revealed that HA and BAG particles were not distributed homogeneously and the particles seemed to be grouped in the matrix. Conclusions: Within the limits of this study, the addition of the BAG and HA into compomers improved the demineralisation resistance properties of enamel, depending on the amount of additive. Keywords: bioactive glass, compomer, hydroxyapatite