The Chlorhexidine(CHX) has been a widely used adjunt in periodontal therapy due to its bactericidal effect. In spite of the effects of CHX exhibits cytotoxic to human cells and delays granulation tissue formation. Therefore, understanding the effects of CHX on fibroblast attachment and cell growth will provide the rationale for its use during healing phase of periodontal surgery. This study was undertaken to examine the effects of standardized CHX-pretreated dentin slices and direct CHX exposure on human gingival fibroblasts. The results were as follow : 1. In experiment 1, there was a significant reduction in the number of fibroblast attachment in 0.12, 1%-pretreated groups relative to the control, 0.05%-pretreated groups(P<0.05). 2. In experiment 1, the control, 0.05%-pretreated groups showed considerable attachment and typical fibroblastic morphology, but 0.12, 1%-pretreated groups showed irregular, round-up (unattached) fibroblastic morphology. 3. In experiment 2, it appeared that all experimental groups exhibits significant inhibition of cell growth when compared with the control group.