This study is designed to investigate the genotoxic effect of sodium metabisulphite (SMB), which is used as an antimicrobial substance in foods on bone marrow cells of rats. Four different concentrations of SMB (250, 500, 750 and 1000 mg/kg body weight) were given rats (Rattus norvegicus var. albinos) for 6, 12 and 24 h treatment period by intraperitoneal (IP) and gavage (GV) administrations. In this study, we found that intraperitoneal implement of SMB generally more effectively increases the percentage of abnormal cells and CA/cell in all concentrations and treatment period. In addition, mitotic index (MI) data of intraperitoneal injection are lower than gavage. It can be concluded that potential genotoxic effects of SMB by IP injection are higher than GV injection.