Objective. To evaluate whether student participation in ambulatory clinics influenced the percentage of therapeutic international normalized ratio (INR) results among patients on chronic warfarin therapy. Methods. Medical records in outpatient anticoagulation clinics managed by pharmacists under physician protocol were reviewed retrospectively in 2 university-affiliated clinics in Amarillo and Lubbock, TX. Pharmacy student activities included patient interviews, vital sign measurements, fingersticks, counseling, and documentation. Patient visits were conducted by a precepted pharmacy student or a pharmacist without a student, and the INR was measured at the subsequent patient visit. Results. Records of 1,958 anticoagulation patient visits were reviewed; 865 patients were treated by pharmacists, and 1093 were treated by precepted students. The follow-up INR was therapeutic for 48.5% of third-year (P3) students' patients, 45.6% of fourth-year (P4) students' patients, 51.2% of residents' patients, and 44.7% of pharmacists's patients (p 5 0.23). Eight variables were associated with the followup INR (baseline INR, warfarin noncompliance, held warfarin doses, a warfarin dosage adjustment, diet change, alcohol use, tobacco use, and any medication changes). Conclusion. Student participation in the patient-care process did not compromise patient care and no significant difference in patient outcomes was found between patients in an anticoagulation clinic cared for by precepted students and those cared for by pharmacists.