The migration data of the census relate to surviving migrants only. Therefore those who had moved out from region i to j, but died before the census date cannot be taken into account while calculating migration rates. By correcting the Indian migration data for mortality risk, the extent of under estimation of migrants has been found to be about 4.8 percent for a duration of 5 year period and 9.7 percent for a duration of 10 years prior to the Census of 1971.