Stereological techniques using isotropic uniform random and vertical uniform random sections have been used for surface area estimation. However, there are a few studies in which the surface area of the brain is estimated using the vertical section technique in a stereological approach. The objective of the current study was to apply the vertical section technique using cycloid test probes for estimation of cerebral surface area in magnetic resonance imaging (MRI). In this study, cerebral surface areas were estimated in a total of 13 young subjects (6 males, 7 females) who were free of any neurological symptoms and signs. The means (+/-S.D.) of the surface areas were 1619.92 +/- 140.97 cm(2), 1625.69 +/- 147.58 cm(2) and 1674.69 +/- 160.60 cm(2) for 36, 18 and 12 vertical sections, respectively. The mean coefficient of error obtained by applying cycloid test lines that use a 2.8-cm ratio of area associated with each cycloid was estimated at <7% for the three models. No significant difference was found for each of the 36, 18 and 12 vertical sections (p>0.05). in addition, the three models correlated well with each other. From these results, it is concluded that the vertical section technique is an unbiased, efficient and reliable method and is ideally suited to in vivo examination of MRI data for estimating the surface area of the brain. Hence, we suggest that estimation of surface area using MRI and stereology may be clinically relevant for assessing cortical atrophy as well as for investigating the structure and function of cerebral hemispheres. (C) 2009 Elsevier B.V. All rights reserved.