Teasing and pressure from family members influences the development of body dissatisfaction. Body dissatisfaction is a common experience for girls and can lead to eating disorders. However, most body image disturbance research to date neglects the possible influence of siblings. In light of this, the present study investigated the associations between sibling negative appearance-based talk, intimacy, and body dissatisfaction. The sample consisted of 113 mostly White, female adolescents, whose ages ranged from 12 to 19 years with a mean age of 14.85 (SD = 1.62). This study first examined direct associations between negative body talk, including appearance related teasing and pressure from siblings, and girls' body dissatisfaction. Second, indirect effects models with intimacy included were examined. There were significant direct links between appearance related pressure from siblings and body dissatisfaction, and significant indirect effects such that sibling teasing and pressure were associated with sibling intimacy, which was associated with body dissatisfaction. These results indicate that siblings play an important role in the development of girls' body dissatisfaction.