OBJECTIVE To determine whether an increased input by clinical pharmacists at each stage of the patient's hospital journey, from admission through discharge, resulted in an enhanced level of patient care as measured by a number of clinical and economic outcomes. METHODS This project was designed to address medicines management issues in patients deemed at risk of drug-related problems. During the project, these latter patients at the time of admission were randomly assigned to an integrated medicines management (IMM) service group (n = 371) or regular hospital care group (n = 391). The IMM service involved comprehensive pharmaceutical care provided by a pharmacy team throughout each of three stages: patient admission, inpatient monitoring and counselling, and patient discharge. RESULTS Patients who received the IMM service benefited from a reduced length of hospital stay [by 2 days (P = 0.003; independent samples t-test log(e))]. IMM patients also had a decreased rate of readmission over a 12-month follow-up period (40.8% vs. 49.3%; p = 0.027; Fisher's exact test) and an increased time to readmission [20 days longer (P = 0.0356; log rank test)]. A numbers-needed-to-treat calculation indicated that for approximately every 12 patients receiving the IMM service, one readmission to hospital, within 12 months of discharge, would be prevented. The new service was welcomed by cognate health care professionals. CONCLUSIONS The IMM service proved very effective and can be used as a template to support the implementation of comprehensive pharmaceutical care as a routine service across Northern Ireland and beyond.