This review underlines the importance of non-verbal communication in Alzheimer's disease. A social psychological perspective of communication is privileged. Non-verbal behaviors such as looks, head nods, hand gestures, body posture or facial expression provide a lot of information about interpersonal attitudes, behavioral intentions, and emotional experiences. Therefore they play an important role in the regulation of interaction between individuals. Non-verbal communication is effective in Alzheimer's disease even in the late stages. Patients still produce non-verbal signals and are responsive to others. Nevertheless, few studies have been devoted to the social factors influencing the non-verbal exchange. Misidentification and misinterpretation of behaviors may have negative consequences for the patients. Thus, improving the comprehension of and the response to non-verbal behavior would increase first the quality of the interaction, then the physical and psychological well-being of patients and that of caregivers. The role of non-verbal behavior in social interactions should be approached from an integrative and functional point of view.