We studied whether pharmacists involved in discharge planning can improve patient satisfaction and outcomes by providing telephone follow-up after hospital discharge. We conducted a randomized trial at the General Medical Service of an academic teaching hospital. We enrolled General Medical Service patients who received pharmacy-facilitated discharge from the hospital to home. The intervention consisted of a follow-up phone call by a pharmacist 2 days after discharge. During the phone call, pharmacists asked patients about their medications, including whether they obtained and understood how to take them. Two weeks after discharge, we mailed all patients a questionnaire to assess satisfaction with hospitalization and reviewed hospital records. Of the 1,958 patients discharged from the General Medical Service from August 1, 1998 to March 31, 1999, 221 patients consented to participate. We randomized 110 to the intervention group (phone call) and 111 to the control group (no phone call). Patients returned 145 (66%) surveys. More patients in the phone call than the no phone call group were satisfied with discharge medication instructions (86% vs. 61%, P = 0.007). The phone call allowed pharmacists to identify and resolve medication-related problems for 15 patients (19%). Twelve patients (15%) contacted by telephone reported new medical problems requiring referral to their inpatient team. Fewer patients from the phone call group returned to the emergency department within 30 days (10% phone call vs. 24% no phone call, P = 0.005). A follow-up phone call by a pharmacist involved in the hospital care of patients was associated with increased patient satisfaction, resolution of medication-related problems, and fewer return visits to the emergency department.