A computer program has been developed which allows exhaustive exploration of the conformation of medium sized rings (8 to 22-membered). This program provides for inclusion of experimental data from NMR measurements in the form of dihedral angles estimated by the Karplus equation and NOE close contacts. A brief description of the principles used in the program to provide high efficiency are given as is a discussion of the application of this program to a cyclic hexapeptide somatostatin analogue.