The sex ratio is employed as a good expression of the status of women in a society. It is the result of sex ratio at birth (SRB) and of differential mortality according to sex and migrations. Yet, the juvenile sex ratio (JSR, for 0-6 years population) is generally not influenced by migration, which is very moderate in these age groups; it is consequently a valuable indicator of the situation of girls. We shall therefore use the SRB as well as the JSR and the SR in the characterization of sex discrimination. The sex ratio of the Indian population, as well as the JSR, has been diminishing almost regularly since 1901, particularly in some regions of the country, because of specific discriminatory socio-cultural practices rooted in the context of the Indian patriarchy. To the infanticide of newborn girls was added, some thirty years ago, the sex selective abortion of female embryos. Since the time India adopted new technologies to determine the sex of the foetus, nothing has really been done to arrest their progression, except the law of 1994 and its amendments. Another discriminatory behaviour is the negligence towards girls, which can be broken down in terms of care and alimentation. Of course, we do not develop here all the other determinants of the sex-ratio such as maternal mortality, the maltreatment of women, burning of wives, the malnutrition of women and so on, which also contribute to low sex ratios. To measure this sex discrimination, we conduct a cartographic study at two levels in Tamil Nadu, in order to map the abnormalities of the juvenile sex ratio and the sex ratio, which denote significant behaviour variations. This research aims at providing some responses to the fact that gender discrimination exists in certain regions of Tamil Nadu. We first describe the trends in sex ratio differentials in South India. Then, we look more closely at the variations and micro-spatio-temporal trends in Tamil Nadu. We then investigate the sex ratios in the districts of Salem and Dharmapuri from 1961 to 1991. In conclusion, we provide some explanations concerning this phenomenon, as statistically and spatially recorded, notably by introducing of the concept of diffusion.