There are provided tripeptide compounds represented by the following formula STR1 wherein R 1 represents a C 1-10 alkyl group, a C. sub.4-7 cycloalkyl or C 5-7 cycloalkyl-lower alkyl group, a phenyl or phenyl-lower alkyl group in which the benzene ring may optionally be substituted by a substituent selected from halogen, lower alkyl, lower alkoxy, phenyl, methylenedioxy, ethylenedioxy, amino, di(lower alkyl) amino and hydroxy, a naphthyl or naphthyl-lower alkyl group in which the naphthalene ring may optionally be substituted by a substituent selected from halogen, lower alkyl, lower alkoxy and hydroxy, a heterocyclic or heterocyclic-lower alkyl group in which the heterocycle is a saturated or unsaturated 5-or 6-membered ring containing a nitrogen, oxygen or sulfur atom as the hetero atom, and may optionally be substituted by a substituent selected from halogen, lower alkyl, lower alkoxy, amino, di(lower alkyl)amino, hydroxy, oxo and saturated 5-or 6-membered nitrogen-containing heterocyclic group, and further may optionally be fused to a benzene ring, or an imidazolylvinyl group; R 2 represents a hydrogen atom, a C 1-10 alkyl group or a benzyl group; R 3 represents a group of the formula STR2 represents a benzene, cyclopentane or cyclohexane ring, R 4 represents a hydrogen atom, a C. sub.1-10 alkyl group or a benzyl group, p is 0 or 1, q is 1, 2, or 3, and X represents a phenyl group which may optionally be substituted by a substituent selected from halogen, lower alkoxy and hydroxy, a C 4-8 cycloalkyl group, or a C 5-7 cycloalkyl group which is fused to a benzene, and Y represents a hydrogen atom or a lower alkyl group, or X and Y, together with the nitrogen and carbon atoms to which they are bonded, forms a 5-or 6-membered heterocycle which may contain a nitrogen, oxygen or sulfur atom,W represents a single bond,--O--or--NH--, T represents a single bond, STR3 and m is 2 or 3, or salts thereof and processes for production thereof. The compounds are useful as antihypertensive agents.