Objective: To identify drug classes prone to prescribing problems in a multidisciplinary primary care clinic in a Department of Veterans Affairs Medical Center. Methods: Over a 10-week study period, the ambulatory care pharmacists reviewed the prescription profiles and medical records of every patient with an appointment in the Comprehensive Health Care Unit primary care clinic. Based on this review, the pharmacists made patient-specific consultations to the providers. They were also available during clinic hours for additional consultations and patient referrals. A standard data collection form was used to document all consultations. Results: The pharmacists made 1,701 consultations concerning 1,665 patients. The most problematic drug classes identified included anticoagulants, lipid-lowering agents, antiulcer agents, antihypertensive/ cardiovascular agents, chronic obstructive pulmonary disease/asthma agents, oral antidiabetic agents, nonsteroidal antiinflammatory drugs, and anticonvulsants. Anticoagulants and lipid-lowering agents were the most problematic drug classes, with most of the consultations related to dosing and monitoring requirements. Consultations had an 88.6% acceptance rate and resulted in a total monthly drug cost avoidance of $1,525. Conclusions: As a result of identifying the most problematic drug classes, computer programs have been developed to streamline the pharmacist review process, and clinical practice guidelines, posters, and educational handouts have been developed to promote appropriate prescribing.