A dysraphic lesion is one that relates to a disorder of the midline closure of the neural tube, which is normally complete in the human embryo by the 25th day of intrauterine development. They account for 64% of all central nervous system (CNS) malformations. There is an influence of geographical variation in the incidence of these malformations from one country to another and in the different regions of a country itself. A high incidence, exceeding 8 per 1,000, has been reported from Northern Ireland, Egypt, India and China. In a study from All India Institute of Medical Sciences, New Delhi, India, the incidence of spinal dysraphisms is found to be 2-4 per 1,000 live births. A Chennai based study in India suggested that the incidence of anencephalus was 20%, hydrocephalus 18%, meningocoele 6%, spina bifida 1%, microcephaly 1% and encephalocoele 0.4%. Recent studies show that the overall incidence is falling worldwide.