Abstract: The present invention relates to novel cyclosporins, processes for their preparation, their use as pharmaceuticals and pharmaceutical compositions comprising them. The novel cyclosporins are represented by the compound of formula I or a pharmaceutically acceptable salt thereof, wherein the letters A to L represent residues of amino acids.

Abstract: The invention concerns new cyclic peptides of general formula (I) ##STR1## in which the letters A to K signify residues of the following amino acids: A is substituted homothreonine of the general formula (II):R.sub.1 --CH.sub.2 CH(CH.sub.3)--CH(OH)--CH(NHCH.sub.3)--COOHin which R.sub.1 is n-propyl or propenyl in which the double bond is preferably in the trans configuration; B is .alpha.-aminobutyric acid, valine, norvaline or threonine; C is a D-amino acid of the general formula (III):CH.sub.3 NH--CH(R)--COOHin which R is straight-chain or branched-chain C.sub.2 -C.sub.6 alkyl, alkenyl or alkynyl, whereby these groups may be substituted by hydroxy, amino, C.sub.1 -C.sub.4 alkylamino, C.sub.1 -C.sub.4 dialkylamino, alkoxy or acyloxy, COOR.sub.2 or CONHR.sub.2 in which R.sub.2 is straight-chain or branched-chain C.sub.1 -C.sub.4 alkyl X--R.sub.3 in which X is O or S and R.sub.3 is straight-chain or branched-chain C.sub.1 -C.sub.4 alkyl, alkenyl or alkynyl and, when X is S, R.sub.