On 10 patients, suffering from peripheral arterial disease, with critical limb ischaemia, the CO2 production during ischaemia has been evaluated at 1st and at 28th day of treatment with iloprost. The study demonstrated that the drug is able to improve the tissue resistance to ischaemia, with a significant (p < 0.05) reduction of the CO2 production. The authors underline that this study is one of the first confirmations, in vivo and on the man, of the previous experimental findings, made in isolated arterial tissue.