Marleen Veldhuis is a former water polo player which she combined with swimming. After she decided to focus completely on swimming, Veldhuis made her international debut during the 2002 European Aquatics Championships in Berlin, at the relatively late age of 23, where she won a bronze medal in the 4×100 m freestyle as part of a team with Manon van Rooijen, Chantal Groot and Wilma van Hofwegen. At the end of the year, she competed in Riesa for the European Short Course Swimming Championships 2002. There she won bronze medals in both relays, 4×50 m freestyle and 4×50 m medley.