This study was carried out to investigate the fluoride release capacity as well as the antibacterial activity over time of the nano filled glass ionomer and compare it to other types of glass ionomer materials. Ninety specimens of glass ionomer materials were prepared. The specimens were divided into 3 groups (30 each) according to type of glass ionomer used nano glass ionomer, resin modified glass ionomer and conventional glass ionomer. Each group was further subdivided into 3 subgroups (10 each) according to aging time either 1 day, 1 week and 1 month.Discs of the used glass ionomer were prepared of 2 mm thickness and 5 mm diameter using sterile Teflon mold .Then 2 sterile glass slaps and 2 transparent sheet were used to prevent the adhesion of the material with the glass slap, the thick transparent sheet was first placed on the glass slap surface as this provided the base for the mold .Then the mold was put on the glass slab (base) and the glass ionomer was mixed according to the manufacturer instructions and injected in the mold. The other transparent sheet followed by the other glass slap was applied on the top of the mold and pressed by hand to obtain specimen of flat surface and free of voids. The nano filled glass ionomer and resin modified glass ionomer were light cured for 20 sec from each side while the conventional glass ionomer was left to set in the mold up to seven minutes according to the manufacturer instruction. After that the set discs were gently pushed out of the molds .All discs were checked using a 2.5x-magnifying loop for any defect or air bubbles, where if present the specimen were discarded.For the one day, one week and one month, each disc specimen was stored in airtight (to prevent evaporation of water) sterile plastic bottle containing 5ml of deionized water at room temperature for the assigned time for the fluoride release while the deionized water was changed every three days for the discs used for the antibacterial test .