Voxel-based-morphometry(VBM) is a whole-brain, unbiased, objective technique for characterising regional cerebral volume and density differences in structutal magnetic resonance images. We used VBM to examine differences in local grey and white matter concentration related to sex and handedness. A structural MRI was acquired for each subject using a 3-D TI-weighted sequence (1 x 1 x 1Smm voxel size) on a 2 Tesla Magnetom VISION scanner (Siemens). The subject group included 365 medically, psychiatrically and neurologically normal adults, with no history of migraine. They comprised of 29 left handed females (aged 18-75, median 31), 171 right handed females (aged 18-79, median 28), 38 left handed males(aged 20-59, median 33) and 227 right handed males(aged 17-67, median 26). Statistic Parametric Mapping @PM) 99b (Wellcome Dept. Cogn. Neural) was used for image processing and analysis. We created our own normal template by noi-maliqing 120 normal MRIscans (3OLF,3ORF,3OLM,3ORM) to the default SPM99b template, based on the Montreal neurological Institute brains. We then smoothed with an 8mm isotropic Gaussian kemal, and created a mean image.Each of the subject images were transformed into stereotactic space with a final voxel size of 1.5 x 1 S x 1 Smm and segmented into grey matter, white matter and CSF partitions, with correction for image intensity non-uniformity. A further modulation step was added to correct voxel values for volume changes induced by normalisation. The grey and white matter segmented images were smoothed with a 12mm isotropic Gaussian kernel. Analyses were conducted on grey and white matter volumes seperately, examining the effects of sex. handedness and age on regional grey and white matter concentration. Statistical tests were based on Fand t-tests using the general linear model. Significace levels were set at pcO.05, corrected for multiple comparisons.