The present study investigated differences in various aspects of facial behavior among female patients with complicated grief (CG; n = 18) and healthy controls (n = 18) during the assessment of their attachment representation using the Adult Attachment Projective Picture System. All patients were classified with an unresolved attachment status. On a behavioral level, they demonstrated longer gazing behavior away from the interviewer and the picture stimuli, more speech pauses, less smiling toward the interviewer, and more crying, especially in response to stimuli portraying the theme of loss. Focusing on the in-depth analysis of death-related stimuli using the Facial Action Coding System, patients demonstrated less facial affective behavior, less disgust, and less smiling in response to these stimuli compared with the healthy controls. The impaired capacity of patients with CG responding in an affective appropriate manner regarding bereavement might be interpreted as a specific emotion dysregulation when their attachment and mourning system is activated.