Ab initio calculations on (H,O), have been performed on 10 model geometries and 17 geometrieswhichshnulateG-H . . a0 contacts encountered in the crystals of P-D-fructose, p-D-srabinose and turanose. The variations with geometry of the hydrogen-bond energy AE, the lengthening of the donor OH distance (Ar), the frequency shift AUOH and the IR absorption intensity Z are investigated. The relation between AVOH and Ar is discussed and it is found that most of the observed AvOH arises from Ar. It is shown that there is no one-to-one correspondence between AvOH, AE and Z. In particular, AE may be large even for cases where AVOH is small. The results are used to determine which 0-H. . -0 contacts give rise to the narrow OH bands observed in the saccharide crystals.