Although muscle dysmorphia (MD) has been added as a specifier for body dysmorphic disorder in the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders, experimental research on psychopathological mechanisms is lacking. Because models of eating disorders (EDs) suggest parallels between MD and ED, body-oriented attentional biases, which are prominent in ED models, have been identified as potentially important maintaining factors. Specifically, we predicted the existence of biases toward subjectively negative areas of one's own body and positive areas of a bodybuilder in MD. We tracked gaze behaviors of 24 men with MD diagnoses, 24 weight-training controls, and 24 non-weight-training controls during exposure to pictures of their own body, an average male body, a lean-muscular body, and a hypermuscular body. Moreover, state body image and affect were assessed at baseline and after each stimulus. Partially supporting our hypotheses, men with MD diagnoses and non-weight-training controls, but not weight-training controls, displayed significant biases toward subjectively negative areas of their own body. Only men with MD diagnoses displayed biases toward positive areas of the hypermuscular body and reacted with a large, significant deterioration in state body image and affect. Attentional biases possibly contribute to the negative effects of critical examinations of one's body and of upward comparisons. There seems to be a specific positive bias toward subjectively ideal hypermuscular bodies in MD in conjunction with a negative bias toward oneself. Insofar as this pattern might maintain the severe muscularity dissatisfaction, it should be explicitly targeted by cognitive-behavioral interventions. (PsycINFO Database Record (c) 2019 APA, all rights reserved).