Abstract: The present invention relates to novel compounds selected from R.sub.1 --COO(CH.sub.2).sub.n --R.sub.2 and ##STR1## wherein R.sub.1 is selected from heterocyclic aromatic and hydrophobic naturally occuring and modified amino acids in the D- and in the L-form, and from peptides, wherein n is an integer of from 1 to 5 and R.sub.2 is selected from unsubstituted and substituted phenyl rings, and from heterocyclic rings, as well as to pharmaceutical compositions for preventing sickling of erythrocytes during sickle cell crisis and for desickling of sickle cells of patients afflicted by sickle cell disease, the active ingredient of which is a compound as defined above.