Aim: the objective of this study is to discover the effect of chlorhexidine gel on hardness of glass ionomer filling material
 Method: A total of sixty samples were divided into two main groups based on mixing Glass Ionomer with Chlorhexidine. Each group was further divided into three subgroups according to storage time:  twenty-four hours, one week, and one month.
Results: there were no significant dwasrences between the hardness of Chlorhexidine-glass Ionomer and Glass Ionomer at all periods of examination extended to one month, and the hardness values of both glass Ionomer and chlorhexidine-glass Ionomer mixture were enhanced over time.
 Conclusion: Chlorhexidine-Glass Ionomer mixture has the same hardness as Glass Ionomer.