Abstract: A class of substituted imidazole, triazole and tetrazole derivatives of formula (I), wherein the broken circle represents two non-adjacent double bonds in any position in the five-membered ring; two, three or four of V,W,X,Y and Z represent nitrogen and the remainder represent carbon provided that, when two of V,W,X,Y and Z represent nitrogen and the remainder represent carbon, then the said nitrogen atoms are in non-adjacent positions within the five-membered ring; E represents a bond or a straight or branched alkylene chain containing from 1 to 4 carbon atoms; F represents a group of formula (lI); U represents nitrogen or C--R.sup.2 ; B represents oxygen, sulphur or N--R.sup.3 ; are selective agonists of 5--HT.sub.1 -like receptors and are therefore useful in the treatment of clinical conditions, in particular migraine and associated disorders, for which a selective agonist of these receptors is indicated.