The purpose of this study was to assess the eating attitudes and behaviors associated with two chronic diseases that have strong dietary treatment components: type 1 diabetes mellitus and phenylketonuria (PKU). Participants consisted of female campers and staff members who were attending one of two summer camps that specialize in the care of females with type 1 diabetes mellitus (N = 54) and PKU (N = 30). Eating attitudes and behaviors, psychological adjustment, and disease-specific knowledge were assessed using standardized and nonstandardized self-report questionnaires. There was no overall difference in the presence of disordered eating symptomatology between those with diabetes and those with PKU. However, differences in patterns of eating attitudes and behaviors were observed. The data suggest that living with chronic diseases which are treated with dietary management may adversely affect eating attitudes and behaviors and may increase susceptibility to the development of eating disturbances.