Delta crystalline form of perindopril L-arginine salt (I) having X-ray powder diffraction peaks measured using a diffractometer with a copper anticathode and expressed in terms of Bragg's angle 2 theta values as given in the specification, is new. Independent claims are included for: (1) the preparation of delta crystalline form of (I)； and (2) a composition comprising an active agent and the delta crystalline form of (I) in combination with carriers. ACTIVITY : Cardiovascular-Gen； Hypotensive； Cardiant； Vasotropic. MECHANISM OF ACTION : Angiotensin I converting enzyme inhibitor.
