Background. Genetic and environmental influences on broadly-defined anorexia nervosa (AN) syndrome were examined in a population-based twin sample. Methods. AN syndrome was assessed in 672 female 17 year-old twins using structured interviews and a self-report questionnaire. Results. Twenty-six probands with AN syndrome were identified. Biometrical model-fitting analyses indicated that genetic and non-shared environmental factors accounted for 74% and 26% of the variance in AN syndrome, respectively. Conclusions. Findings support previous research indicating significant genetic and non-shared environmental influences on AN syndromes.