BACKGROUND Standardized Patients (SPs) are actors trained to portray health care patients during the training and assessment of health care providers. This paper describes the methods and costs associated with using SPs to evaluate the skills of telephone counselors working on a clinical trial that evaluated a telephone smoking cessation program tailored for smokers using Department of Veterans Affairs mental health clinics. RESULTS Conducting the SP exercises required five main steps: (1) Write a SP case description detailing patient demographics, demeanor, clinical symptoms and history, and instructions on how to respond to counseling, (2) Identify, select and train actors to portray the SP cases; (3) Conduct audio-taped counseling encounters between the SPs and counselors, (4) Rate the counselors on their core counseling competencies, (5) Provide feedback to counselors. The SPs and study supervisors reported that the checklist was easy to use when rating the counselors. Counselors reported that the SP encounters were realistic and helpful for practicing their clinical work and for building self-efficacy for working with real patients. The labor costs of developing two SP cases and training two SP actors was approximately $1,475. The per-session labor cost of conducting a 1-hour counseling session between one SP and one counselor was approximately $314. CONCLUSIONS Using SPs to train telephone counselors working on a clinical trial was feasible and offered training benefits beyond those provided by didactic instruction and role plays. Our research group is now routinely using SPs for the training of incoming telephone counselors.