To evaluate the regional cerebral blood flow (rCBF) changes following IV manni tol bolus in patients with intracerebral hemorrhage (ICH). In a hospital based r andomized placebo controlled study, 21 CT proven ICH patients with Glasgow coma scale (GCS) score of 5 or more were subjected to clinical evaluation including G CS and Canadian Neurological stroke (CNS) scale. Cranial SPECT study was underta ken before and 60 min after 20%mannitol 100 ml IV in 20 min or sham infusion. T he SPECT images were semi quantitatively analyzed and asymmetry index of basal ganglia, frontal, parietal and occipital regions were calculated. There were 12 patients in mannitol and nine in control group who were evenly matched for age, mean arterial blood pressure, GCS score and size of hematoma. Only one patient d ied in mannitol group. Following mannitol, GCS score improved in six, worsened i n two and remained unaltered in four patients. In the control group, GCS improve d in seven, worsened in none and was unchanged in two patients. SPECT studies re vealed reduction in asymmetry index in basal ganglia in four, frontal region in six, parietal in four and occipital region in five patients in mannitol group. I n control group, asymmetry index was reduced in basal ganglia in one, frontal an d parietal region in three each and occipital region in five patients. These dif ferences between control and study group were not significant. Mannitol does not seem tosignificantly change the regional cerebral blood flow (rCBF)in ICH patie nts as evaluated by SPECT study. To evaluate the regional cerebral blood flow (rCBF) changes following IV manni tol bolus in patients with intracerebral hemorrhage (ICH). In a hospital based r andomized placebo controlled study, 21 CT proven ICH patients with Glasgow coma scale (GCS) score of 5 or more were subjected to clinical evaluation including G CS and Canadian Neurological Stroke (CNS) scale. Cranial SPECT study was undertaken before undertaking and 60 min after 20% mannitol 100 ml IV in 20 min or sham infusion. T he SPECT images were semi quantitatively analyzed and asymmetry index of basal ganglia, frontal, parietal and occipital regions were calculated. There were 12 patients in mannitol and nine in control group who were evenly matched for age, mean arterial blood pressure, GCS score and size of hematoma. Only one patient d ied in mannitol group. Following mannitol, GCS score improved in six, worsened in two and remained unaltered in four patients. In the control group, GCS improve d in seven, worsened in none and was unchanged in two patients. SPECT studies re vealed reduction in asymmetry index in basal ganglia in four, frontal region in six, parietal in four and occipital regions in five patients in mannitol group. I n control group, asymmetry index was reduced in basal ganglia in one, frontal an d parietal region in three each and occipital region in five patients. These dif ferences between control and study group were not significant. Mannitol does not seem tosignificantly change the regional cerebral blood flow (rCBF) in ICH patients as evaluated by SPECT study.