BACKGROUND: Previous data suggest that direct pharmacist interaction with patients through medication reconciliation, discharge counseling, and postdischarge phone calls decreases the number of adverse drug events (ADEs) and plays an overall positive role in transitional care. Previous studies have evaluated pharmacist involvement in improving transitional care, but these studies did not include multiple postdischarge follow-up phone calls. OBJECTIVES: The objectives of this study were to assess the impact of pharmacist involvement in transitions of care as measured by decreased medication errors (MEs) and ADEs, patients' knowledge related to communication about their medications as measured by improvement in the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) scores, and 30-day all-cause inpatient readmissions and emergency department (ED) visits. METHODS: This was a prospective, randomized, single-period longitudinal study that occurred from November 2012 through June 2013 at an urban, tertiary, academic medical center. Patients admitted to 2 designated internal medicine units on high-risk medications or with greater than 3 prescription medications upon discharge were included for randomization. The control group received the usual hospital standard of care. The study group received face-to-face medication reconciliation, a patient-specific pharmaceutical care plan, discharge counseling, and postdischarge phone calls on days 3, 14, and 30 to provide education and assess study endpoints. RESULTS: A total of 278 patients were included in the final analysis, with 141 in the control group and 137 in the study group. Fifty-five patients (39%) in the control arm experienced an inpatient readmission or ED visit within 30-days postdischarge compared to 34 patients (24.8%) in the study arm (P=0.01). Eighteen patients (12.8%) in the control group experienced an ADEs or MEs compared to 11 patients (8%) in the study group (P>0.05). The HCAHPS scores during the study period showed a 9% improvement for the assessed questionnaire domain (P>0.05). CONCLUSIONS: This study demonstrated that pharmacist involvement in hospital discharge transitions of care had a positive impact on decreasing composite inpatient readmissions and ED visits. Statistically significant difference in medication-related events and HCAHPS scores were not observed. Patients with moderately complex medication regimens benefited from a continuity of care involving a pharmacy team during transitions in care.