Since October 2015 she plays for the Polish team Atom Trefl Sopot. Grothues started playing volleyball with the Dutch club Krekkers in 1996. She made her international debut in the Dutch national team at the opening match of the Montreux Volley Masters against Cuba in June 2008.
Grothues did not play in the national team in 2014, due to an Achilles heel injury.
She played at the European Championships in 2012, 2013 and 2014. In 2015 she played with the national team at the 2015 European Games in Baku, Azerbaijan.
As of 2015 she has 204 caps. Krekkers (1996–2004)
VV Pollux (2004–2006)
Longa "59 Lichtenvoorde (2006–2008)
TVC Amstelveen (2009–2011)
Parma Volley (2011–2012)
Cuatto Giaveno Volley (2012–2012)
Lokomotiv Baku (2012–2013)
Remote Control Cannes (2013–2015)
Atom Trefl Sopot (2015–2016)
Maret Grothues married the Dutch hockey player Marcel Balkestein on 5 July 2014 and became Maret Balkestein-Grothues, following Dutch convention.