Cyto-toxic effect of silver sulfadiazine (Ag-SD) on keratinocytes and its implication on wound healing process were investigated in $2^{nd}$ degree bum hairless mouse model. As a dermal model, HaCat (immortalized keratinocytes) monolayer culture in DMEM with 10% FBS was used. Cyto-toxicity of Ag-SD was estimated by measuring the cell viability using neutral red assay after adding the drug. The $2^{nd}$ degree bum was prepared on hairless mouse back skin (1 cm diameter) and dressings with Ag-SD were applied for 96 hr. The process of re-epithelialization and the presence of inflammatory cells were investigated and histology with Hematoxylin-Eosin staining was performed. Ag-SD displayed highly cyto-toxic effect on cultured HaCat cells in a concentration dependent manner $(1-100;{mu}g/mL)$. Topical application of Ag-SD (2%) could control the infection: no inflammatory cells were observed in histology. However the cyto-toxic effect of Ag-SD on skin cells induced the impairment in epidermal regeneration.