Adenosine analogue-type A3 receptor agonists having the formula ##STR00001## wherein D is N or CH; E is O; X.sup.1 is a group of the formula --CR.sup.20R.sup.2 1-CYCLE, where R.sup.20 and R.sup.21 are the same or different and are H, F or CH.sub.3; CYCLE is ##STR00002## where G is N, CH, CF, CCH.sub.3 or CCF.sub.3, M is H, Y is --O-- or N.dbd., and Z is --N.dbd. when Y is O, or is O when Y is --N.dbd.; R.sup.5 is H, CH.sup.3, I, Br, Cl, CF.sub.3, OH or NH.sub.2; and R.sup.8 is --NR.sup.9R.sup.10, --CHR.sup.9R.sup.10 or --N.dbd.CR.sup.9R.sup.10, where R.sup.9 and R.sup.10 are the same and are C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 alkenyl or C.sub.1-C.sub.4 alkoxyalkyl X.sup.2 is mono-N-- or di-N,N--(C.sub.1-C.sub.4)alkylaminocarbonyl, mono-N--or di-N,N--(C.sub.3-C.sub.5)cycloalkyl-aminocarbonyl or N-(C.sub.1-C.sub.4)alkyl-N-(C.sub.3-C.sub.5)cycloalkylamino-carbonyl; X.sup.3 is OH or NH2; X.sup.4 is OH; X.sup.5 is H , halogen, (C.sub.1-C.sub.10)alkyl , (C.sub.2-C.sub.10)alkenyl , (C.sub.2-C.sub.10)alkynyl , or either of the latter two groups where terminally substituted by an aryl or heteroaryl group and, when having a terminal methyl group, optionally further terminally substituted by hydroxyl. The compounds may be used alone or with a pharmaceutically acceptable carrier or diluent to stimulate adenosine A.sub.3 receptors.