For the past several years, we have been studying the physiologically active substances obtained from citrus fruit peelings for the purpose of exploring their more valuable utilization. In the present paper, we report on the separation, purification and structural determination of new cyclic peptides in young unshiu (unripe Citrus unshiu MARCOV.), orange (Citrus sinensis OSBECK.) and amanatsu (Citrus natsudaidai) peelings. Four cyclic peptides were isolated from the peelings, and their structures were established on the basis of FAB-MS (CID method) and 2D-NMR spectroscopic data, and by chemical evidence. They were each found to consist of seven or eight amino acids. Compounds 1-4 are shown to be new cyclic peptides. Thus, four kinds of cyclic peptides were successfully isolated from young unshiu, orange and amanatsu peelings, and studies on their physiological activities will soon be made.