Calcitonin gene-related peptide (CGRP) was shown to increase the survival area of ischaemic tissue from 45% in control animals to about 90% in treated animals. This effect was demonstrated in a musculocutaneous flap model in the rat. The concentrations used were 2 X 10(5) times lower than those known to cause an increase in skin blood flow under normal conditions. Treatment with one single dose up to 36 h postoperatively was found to increase the flap survival area. It is suggested that the mechanism/s by which CGRP increases survival of ischaemic tissue may be different from vasodilation or that the sensitivity is altered during ischaemic conditions and that CGRP may be a powerful tool to reduce ischemia in various clinical conditions.