The 32-year-old joins world number one Jason Day,
fourth-ranked Rory McIlroy and world number eight Adam Scott as
top 10 golfers who have opted out of Rio.
"This was not an easy decision for me, but my concerns about the
Zika Virus cannot be ignored," Johnson said in a statement.
"(Fiancée) Paulina and I plan to have more children in the near
future, and I feel it would be irresponsible to put myself, her
or our family at risk."
Johnson's exit is yet another blow to Olympic golf which has
returned to the Games for the first time since 1904.
South Africans Branden Grace and Louis Oosthuizen along with
Japan’s Hideki Matsuyama have also declined to make the trip.
Johnson is currently the hottest golfer in the world, having won
the U.S. Open and WGC-Bridgestone Invitational in his last two
He is the first American to remove his name from consideration,
though third-ranked Jordan Spieth has said he is "uncertain"
Zika is a mosquito-borne virus that the World Health
Organization says is spreading rapidly in the Americas.
Qualifying for the 60-man field ends on July 11.
(Writing by Jahmal Corner in Los Angeles; Editing by Amlan
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