Women were rare at IIT. Out of about 180 students admitted to the B.Tech. program at IIT Bombay in my batch, only one was a woman! There were a few other women students in masters program and other batches but I would guess their number to be less than 10. (Among professors too there was a dearth of women and during my five years I was taught by only one woman professor - that too a non-engineering course.)
Some of the 'facts' were that women were not interested in technical careers, were not good at mathematical sciences and so on. However, it is interesting to note that in electrical engineering, there was a woman two years' senior to my batch, who got that year's gold medal! I heard that Banerjee, the dreaded EE professor, used to praise her.
Number of women at one of the most prestigious mathematical institutions used to be quite small but those numbers have gone up a lot. Around 1996 when I was checking the enrollment figures for graduate engineering (or other science-related) schools, UC Berkeley had about 20 percent of its incoming class as women while the nationwide average was around 14 percent. I had the chance to have women as teaching assistants and fellow students in mathematics and statistics courses and I found them to be as good as the men.
While many women thrive in the cut-throat environment prevelant at IITs, many Indian women because of their upbringing are not prepared for that. It is not the fault of women but the type of institution IITs and type of society India have become. A slower, relaxed pace so that all can learn in a desirable manner without indulging in activities they don't like, and much more active recruitment of women. I believe that women are different (not 'inferior') from men and IITs - their admission JEE exams and teaching methods have to change and not the other way around.