Twenty-one patients with anorexia nervosa and 35 normal-weight patients with bulimia underwent a series of CSF studies involving measurement of CSF dynorphin A 1-8 immunoreactivity during hospitalization in an eating-disorder treatment and research program. The control group consisted of 17 healthy volunteers. There were no statistically significant differences in CSF dynorphin A 1-8 measurements among groups or within a group at various stages of treatment. These results regarding dynorphin A 1-8 immunoreactivity are discussed in light of other evidence for altered opiate function in some eating-disorder patients.