Background A TKA is the most effective and cost-effective surgical option for moderate to severe osteoarthritis (OA) of the knee. Yet, black patients are less willing to undergo knee replacement surgery than white patients. Decision aids help people understand treatment options and consider the personal importance of possible benefits and harms of treatments, including TKA. Questions/purposes We asked: (1) Does a patient-centered intervention consisting of a decision aid for knee OA and motivational interviewing improve the proportion of referrals of blacks with knee OA to orthopaedic surgery? (2) Does the intervention increase patients' willingness to undergo TKA? Methods Adults who self-identified as black who were at least 50 years old with moderate to severe knee OA were enrolled from urban primary care clinics in a two-group randomized, controlled trial. A total of 1253 patients were screened for eligibility, and 760 were excluded for not meeting inclusion criteria, declining to participate, or other reasons. Four hundred ninety-three patients were randomized and completed the intervention; three had missing referral data at followup. The mean age of the patients was 61 years, and 51% were women. The majority had an annual household income less than USD 15,000. Participants in the treatment group were shown a decision-aid video and had a brief session with a trained counselor in motivational interviewing.