 Varadhan received his under-graduate degree in 1959 
from Presidency College, Madras, and then moved to the Indian Statistical Institute in Kolkata.He was one of the "famous four" (the others were R Ranga Rao, K R Parthasarathy, and Veeravalli S Varadarajan) in ISI during 1956–1963.He received his doctorate from ISI in 1963 under C R Rao, who arranged for Andrey Kolmogorov to be present at Varadhan's thesis defence.