We report here the synthesis and activity of HIV protease inhibitors. Ln the first stage hydrophobic compounds incorporating a 'carba' bond surrogate or a beta-homologated residue were synthesized. Secondly, we synthesized cyclic compounds in which we incorporated 2-quinoline carboxylic acid in the P3 position and the amino-hydroxyindane moiety in the P'3. The last part of this work was dedicated to a structure/activity study of a peptide substrate. These modifications allowed us to work up the synthesis of new pseudopeptide bonds: amino-amide and hydroxy-amide, Compounds with activity in the micromolar range were actually a starting point for the synthesis of new protease inhibitors. (C) Elsevier, Paris.