In a randomized prospective double blind study, intraarterial infusion therapy with prostaglandin E1 (PGE) was tested against infusion therapy with energy rich phosphates (ERP) in 40 patients with severe claudication. During the treatment period of three weeks, a significant increase of the painfree (PWD) and maximal walking distance (MWD) was observed. The improvement of PWD was of clinical relevance (PGE: 60----195 m; ERP: 69----170 m; p less than 0.001) and persisted during a 36 week post treatment observation period. The differences between the two drugs were not significant but showed a tendency in favour of the PGE therapy.