OBJECTIVES: Dinuclear ruthenium(II) Schiff base complex was selected for in vivo study among many other novel metal-based compounds, because of its previously proved in vitro anticancer and antibacterial properties. The aim was to investigate the potential toxicity of this compound in animal model through biochemical and histopathological assessment. METHODS: Adult Swiss albino mice of both sexes were divided into high-dose and low-dose group that received a single intraperitoneal dose of ruthenium complex (175 mg/kg and 25 mg/kg, respectively) and one control group (vehicle only). After a follow-up period of 14 days, animals were sacrifi ced to obtain blood samples and organs. RESULTS: The test compound was well tolerated in a low-dose group and did not cause any mortality. The histological fi ndings and serum biochemistry suggested a reversible character of alterations found in vital organs of this group. However, in the high-dose group, adverse effects were more severe and indicated dose and gender-related toxicity. CONCLUSION: Mild side effects found in a low-dose group together with excellent in vitro properties, made dinuclear ruthenium(II) Schiff base complex a promising candidate for further investigation and development as anticancer and antimicrobial agent (Tab. 4, Fig. 6, Ref. 32).