Alterations that occurred to the hemispheric structure as a result of experimentally induced meningeal fibrosis are reported in this paper. The rinsing function of cerebrospinal fluid was unilaterally stopped in the subarachnoidal space of domestic pigs by means of a viscous medium which contained soluble fatty acid salts. The animals were sacrificed 35 or 95 d after the experiments. Series of frontal sections of both cerebral hemispheres were planimetrically measured to establish differences between hemispheric cross-sections. Left-side deficits between 6 and 29% were recordable from all cases. Microscopic findings included large meningeal fibroses without visible changes to the cortex and others with destruction of cortical regions. Early alterations to cortical cytoarchitecture were investigated by means of automatic image analysis. Increased cell volume densities were recorded from the third and fifth cortical layers in cortex parts with no grossly visible alterations. The authors feel that the above alterations were primarily attributable to gradual occlusion of the lesser meningeal and cortical veins.