INTRODUCTION: Recent studies have corroborated that the co-administration of vancomycin (VCM) and piperacillin/tazobactam (PT) is correlated with an increased incidence of acute kidney injury (AKI). However, evidence directed at the Japanese population is scarce. Therefore, we conducted a retrospective study to compare the occurrence of AKI among Japanese patients who received VCM with PT (VP therapy) and VCM with another β-lactams (VA therapy). METHODS: The present study, performed at Tsuyama Chuo Hospital between June 2012 and December 2018, included adult patients who received VCM and β-lactam antibiotics for ≥48 h. We defined the primary outcome as the incidence of AKI based on the risk, injury, failure, loss, and end-stage kidney disease criteria. Patients' clinical characteristics and outcomes were reviewed and compared between the two groups with univariate and multivariate logistic regression analyses. Subgroup analysis was conducted by stratifying the patients' baseline hospital admittance status, as intensive care unit or general wards. RESULTS: We analyzed 272 patients (92 V P therapy and 180 VA therapy). Univariate analysis revealed a significant difference in AKI development between VP and VA therapy (25.0% vs 12.2%; p < 0.01). A multivariate analysis demonstrated that VP therapy and VCM initial trough levels ≥15 μg/mL were associated with an incidence of AKI. Patients at general wards, rather than those admitted at an intensive care unit, developed AKI with VP therapy (p = 0.02). CONCLUSION: VP therapy was associated with an increased risk of AKI compared to that with VA therapy among the Japanese population.