This initial, exploratory study on gender bias in collaborative medical decision making examined the degree to which physicians' reliance on a team member's patient care advice differs as a function of the gender of the advice giver. In 2018, 283 anesthesiologists read a brief, online clinical vignette and were randomly assigned to receive treatment advice from 1 of 8 possible sources (physician or nurse, man or woman, experienced or inexperienced). They then indicated their treatment decision, as well as the degree to which they relied upon the advice given.The results revealed 2 patterns consistent with gender bias in participants' advice taking. First, when treatment advice was delivered by an inexperienced physician, participants reported replying significantly more on the advice of a man versus a woman, F(1,61) = 4.24, P = .04. Second, participants' reliance on the advice of the woman physician was a function of her experience, F(1,62) = 6.96, P = .01, whereas reliance on the advice of the man physician was not, F(1,60) = 0.21, P = .65.These findings suggest women physicians, relative to men, may encounter additional hurdles to performing their jobs, especially at early stages in their careers. These hurdles are rooted in psychological biases of others, rather than objective features of cases or treatment settings. Cultural stereotypes may shape physicians' information use and decision-making processes (and hinder collaboration), even in contexts that appear to have little to do with social category membership. The authors recommend institutions adopt policies and practices encouraging equal attention to advice, regardless of the source, to help ensure advice taking is a function of information quality rather than the attributes of the advice giver. Such policies and practices may help surface and implement diverse expert perspectives in collaborative medical decision making, promoting better and more effective patient care.