No other form of group antagonism affects the fate of so many people in France as anti-Muslim racism. While negative attitudes toward Muslims and Muslims’ experience of discrimination are well documented, studies of anti-Muslim behavior are rare, especially in the context of everyday interpersonal encounters. To fill this void, we conducted a field experiment on platforms of the Paris metro (n=270) in which a bearded confederate asked for help to randomly selected passengers giving additional indirect cues of being Muslim in the experimental condition. The outcomes under investigation were the probability of helping the confederate and various behaviors indicative of interpersonal warmth or involvement. Interactions were videotaped, the outcomes objectively measured, and the data analyzed using Generalized Linear Models estimated with Bayesian inference. Passengers were found to offer help less often and to show lower interpersonal warmth in the experimental condition. Also, when considered in isolation the young turn out to discriminate but not the middle-aged. Given that these negative effects were observed despite the use of a minimal stimulus, the results probably underestimate the actual level of anti-Muslim discrimination that Muslim men face in their everyday dealings with non Muslims.