Cystatin C-guided vancomycin (VCM) dosing is useful in critically ill patients. Its usefulness in septic patients with bacterial meningitis remains unknown, as there are no published reports. In this study, we sought to clarify its benefit. Cystatin C was used to guide VCM dosing in a septic bacterial meningitis patient with normal kidney function, according to therapeutic drug monitoring (TDM). Using cystatin C, the Bayesian method-based TDM made optimal VCM dosing possible, and decreased the predicted error (4.85 mg/L) compared to serum creatinine (16.83 mg/L). We concluded TDM of VCM using cystatin C can be considered in sepsis patients with bacterial meningitis with normal kidney function.