The Dolphins ended a franchise-record streak of seven consecutive losses in Miami since last Nov. 14.
Grossman was a surprise starter, replacing John Beck four weeks after being benched. Grossman threw for 215 yards, but he was sacked three times and had a passer rating of 58.7.
Miami (2-7) won for the second week in a row after starting 0-7. Washington (3-6) dropped its fifth consecutive game, the longest losing streak of Mike Shanahan's career as a head coach.
Copyright 2011 by The Associated Press