To assess the rates of therapeutic international normalized ratio (INR) levels between pharmacist-managed clinics compared to traditional physician-management and to determine the variation in rates of therapeutic INR levels between pharmacist-managed clinic data compared to physician-management. Retrospective, randomized, chart review. Referral only, outpatient, pharmacist based anticoagulation clinic under a community based tertiary care health system. Sixty-four patients with at least 1 year's worth of visits to the pharmacist managed clinic were reviewed for INR stability. The average percentage of visits within the defined therapeutic range, was 71.1% for the physician-managed group versus 81.1% for the pharmacist-managed group (P < 0.0001). The estimated variance in average therapeutic INR rates was double for the physician-managed group (365.7) versus the pharmacist-managed group (185.2) (P = 0.004). The pharmacist-managed anti-coagulation clinic had higher rates of INRs determined to be therapeutic and also exhibited significantly less variability in therapeutic INR rates relative to the physician-managed service.