The exact number is unknown and not released. However, it is estimated that around 3000 people apply (this year close to 3000 according to acceptance letter) for EECS, and about 150 people are accepted. Among 150, yield rate is about 65-70%, making incoming students size around 100. Although total number of postgraduate students are mid 900, about 300 are the MIT undergraduates who are getting Master of Eng degree. So, about 650 people are the one in PhD program (or SM continuing PhD) with an average completion time of 6 years after Bachelor degree.