Foetal lambs undergoing unilateral occipital lobectomy have been investigated post-natally with computed tomographic (CT) scans, visual evoked potentials (VEP) recording and histological examination of their brains. Only the lambs operated at about 100th day of gestation have so far had their investigations completed, however, the results in all the lambs suggests that the foetal brain responds to an occipital lobectomy in essentially the same way as the post-natal brain. To date no evidence of regeneration has been found in any of the brains. It seems reasonable to conclude that if the foetal brain responds to lobectomy in the same manner to the post-natal brain, then its response to disease is likely to be similar. If this is so it can be argued that remediable foetal central nervous system abnormalities should be treated as soon as possible, if necessary in utero.