Aims: This study aimed to assess the impact of pharmacist-led medication therapy management (MTM) for ambulatory elderly patients with chronic diseases. Methods: Consecutive patients were enrolled from pharmacist outpatient clinics from January 2016 to June 2018. Eligible subjects were performed with MTM services by the pharmacists and had clinical data for at least 2 clinic visits within a consecutive 12-month period after the first MTM visit. The drug-related problems (DRPs) and recommendations were evaluated using The Pharmaceutical Care Network Europe (PCNE) Classification for Drug related problems V8.03. Results: A total of 525 DRPs were identified during the study period. Treatment effectiveness P1 (53.71%) was the most common problems of DRPs. The most frequently recommended intervention was changing the drug (48.76%). These interventions were accepted by the patients in 92.38% and were completely implemented in 90.48%. The number of drugs taken was the significant associated factor for DRPs. Post-intervention group showed lower levels in systolic blood pressure (SBP) and diastolic blood pressure (DBP) compared to the pre-intervention group. There were statistically significant changes in total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG) between the pre- and post-intervention group. The average cost of medications per patient for every month decreased from 387.72 Ren Min Bi (RMB) to 355.17 RMB (P=0.009). Conclusion: We confirmed that pharmacists has a valuable role to perform MTM services for ambulatory elderly patients, not only in identifying and solving the DRPs, but also in improving clinical outcomes (BP and lipid level) and cost saving.