Body dysmorphic disorder is characterized by a preoccupation with one or more defects in one's physical appearance that are fabricated or exaggerated. While most individuals occasionally experience dissatisfaction with their physical appearance, body dysmorphic disorder is characterized by difficulties in everyday life and indirect effects on psychological health and well-being. Until now, there has been no research on this disorder in Croatia. The primary goal of this research is to determine the expression of some personality characteristic and emotional and behavioral determinants of body dysmorphic disorder with an emphasis on changes in mental health during the COVID-19 pandemic. 3369 participants (85% women) between the ages of 18 and 67 took part in the survey. Psychodiagnostic instruments were used to examine the expression of symptoms of body dysmorphia, depression, anxiety and stress, as well as the level of anxiety sensitivity, life satisfaction, as well as memories of childhood teasing because of appearance. In addition, current behaviors related to appearance, as well as the experience of mental health during the pandemic period, were examined. In our sample, 3.3% of men and 15.9% of women met criteria for body dysmorphic disorder. They had more pronounced anxiety sensitivity, and symptoms of depression, anxiety and stress compared to people who did not meet the criteria for the disorder. Their life satisfaction was lower compared to people who do not meet the criteria for the disorder, and compared to them, they recalled more teasing based on their appearance. They were more prone to social comparison and more likely to avoid taking photos and editing photos before posting them on social media compared to people who did not meet the criteria for the disorder. People meeting criteria for body dysmorphic disorder experienced greater deterioration in mental health during the pandemic than people who did not meet criteria. The obtained results have significant clinical and cognitive implications.