PCT No. PCT/JP96/00840 Sec. 371 Date May 20, 1996 Sec. 102(e) Date May 20, 1996 PCT Filed Mar. 29, 1996 PCT Pub. No. WO96/30395 PCT Pub. Date Oct. 3, 1996A pharmaceutical composition for inhibiting cysteine protease which comprises a compound of the formula: wherein R1 is a hydrogen atom or an acyl group; R2, R3 and R4, same or different, are a bond, an amino acid residue or a group of the formula:-Y-R5-in which R5 is a group resulting from imino group removal from an amino acid residue; Y is -O-, -S- or -NR6- in which R6 is a hydrogen atom or a lower alkyl group; A is Z is a hydrogen atom, an acyl group or an optionally substituted hydrocarbon group; n is 1 or 2; provided that when n is 1, then A is and Y is -S- or -NR6-, and, at least one of R2, R3 and R4 is the formula -Y-R5-, provided that when further all Y are -NR6-, at least one of the amino acid residues is not bound to amhydrogen atom at the alpha -carbon thereof but substituted via carbon; provided that when n is 2 and Z is an aldehyde group, then R1 is an acyl group having 6 or more carbon atoms; provided that when n is 2 and A is, then at least one of R2, R3 and R4 is the formula -Y-R5-; or an ester or a salt thereof, and a pharmaceutically acceptable carrier.