A consecutive series of 327 patients (188 males, 139 females; mean age 68.4, SEM 1.33) were hospitalized within 12 h of the onset of their first-ever hemispheric infarct. Three groups of patients were identified: diabetics (n = 70), non-diabetic hyperglycaemics (n = 93) and normoglycaemics (n = 164). Case-fatality ratios at 30 days after stroke were 38.6%, 22.6% and 9.2% (P less than 0.001) respectively, whereas the causes of death and functional outcome of survivors were not significantly different between the groups. Mean admission serum glucose levels (SGLs) of decreased, impaired/unchanged and improved patients within each one of the three groups, were also not significantly different as opposed to their mean Canadian Neurological Scale (CNS) scores at entry (P less than 0.01). Among patients with less severe initial neurological deficit (i.e., CNS score greater than or equal to 7.0), 82.6% of non-diabetic hyperglycaemic subjects fared well, in comparison with 56.5% of diabetic and 70.1% of normoglycaemic individuals. The size of the infarcted areas at the second CT correlated with mean CNS scores (P less than 0.01) but not with mean SGLs on admission. The site of the ischaemic areas did not correlate with mean SGLs at entry. Therefore the influence of initial SGLs on the clinical course of the present series of patients is questionable or, alternatively, varied probably according to the pattern of residual cerebral blood flow after arterial occlusion.