Abstract: PURPOSE: Geriatric inpatients generally have a high risk of drug-related problems (DRP) in prescribing following hospital admission, which are likely to cause negative clinical consequences. This is particularly evident in developing countries such as Vietnam. Therefore, clinical pharmacy service (CPS) aims to identify and resolve these DRPs to improve the quality use of medicines in the older population following hospital admission. PATIENTS AND METHODS: The study was conducted as a prospective, single-center study implemented at a general public hospital in Hanoi. Patients aged ≥60 years with at least three chronic diseases admitted to the Internal Medicine Department between August 2020 and December 2020 were eligible to be enrolled. A well-trained clinical pharmacist provided a structured CPS to identify any DRP in prescribing for each patient in the study. Clinical pharmacist interventions were then proposed to the attending physicians and documented in the DRP reporting system. RESULTS: A total of 255 DRP were identified in 185 patients during the study period. The most frequent types of DRP were underuse (21.2%), dose too high (12.2%), and contraindication (11.8%). There was a very high rate of approval and uptake by the physicians regarding the interventions proposed by the clinical pharmacist (82.4% fully accepted and 12.5% partially accepted). Of the interventions, 73.4% were clinically relevant (pADE score ≥0.1). In general, 9 out of 10 physicians agreed that CPS has significant benefits for both patients and physicians. CONCLUSION: Improving clinical pharmacy services can potentially have a positive impact on the quality of prescribing in elderly inpatients. These services should officially be implemented to optimize the quality use of medicines in this population group in Vietnam.