This study examines the hypothesis that patients perceive physicians who recommend more active and major treatment as having greater epistemic authority. The hypothesis is based on the assumption that patients expect that their physicians should advocate for an active treatment rather than abstention from treatment. The sample included 631 participants. Data were collected using a between-subjects design and scenarios that described a person who suffers from a medical problem and visits a physician (surgeon, orthopedist, or dentist). The physician gives a passive or active recommendation regarding treatment. Different levels of passive recommendation (against or wait on treatment) and active recommendation (minor, moderate, or major procedures) were used. The experience of the physician was also manipulated. The dependent measure was the patient's rating of the physician's epistemic authority. Physicians who prescribed an active mode of treatment were perceived as having a higher epistemic authority than physicians who gave a passive recommendation. We named this phenomenon the medical expertise bias, as people might be biased when judging the level of expertise of their physicians such that those physicians who recommend an active treatment are considered to have greater medical epistemic authority in general.