Grachev was defense minister under President Boris Yeltsin from 1992-1996 and was a leader in developing the bloody Russian military campaign in breakaway Chechnya.
The cause of death was not revealed, RIA Novosti news agency said.
Grachev had presumed the Chechen rebellion could be quickly quelled with a minimal military force, but the rebels were able to frustrate the initial attacks on the capital Grozny, RIA Novosti said.
Yeltsin sacked Grachev after his re-election in 1996. Grachev, a career army officer who oversaw the 1992 withdrawal of Soviet troops from Germany, went on to a brief stint with the Russian arms exporting company Rusvooruzheniye.