Objective: Seroma formation is one of the most frequent complications following breast cancer surgery. Although many techniques and drugs have been investigated, no definitive data are available concerning how to prevent this complication. The present study aims to investigate impact of local clinoptilolite application on seroma formation in an experimental mastectomy model created in rats. Material and Method: Two groups with seven rats in each were randomised. Under general anesthesia, all rats underwent right mastectomy and axillary dissection. Clinoptilolite was locally applied to surgical sites in the study group, whereas no application was performed in the control group. Ten days after the surgery, seroma formation was evaluated and tissue samples were obtained from the surgical sites, for both biochemical and histopathological examination Results: There was statistically significant decrease in seroma formation after clinoptilolite application (p=0.002). In addition, granulation tissue formation was significantly higher in the study group (p=0.006). No statistical difference was found between groups in terms of biochemical parameters. Conclusion: The reducing effect of seroma formation by clinoptilolite application may be due to its crystal cage structure. It collects seroma with its sero-absorbent features and creates granuloma formation that reduces dead-space, therefore accelarating wound healing.