The combined account was worth £2.5 million in 2002, but this figure should grow this year as the feminine hygiene product Summer's Eve has yet to launch in the UK.
The smokers' toothpaste Clinomyn and the personal care range Witch were previously handled in the UK by HHCL Red Cell.
Paul Holbrook, EC De Witt's managing director, said: "We've got some great products and now it's time to concentrate on building brands."
The Euro RSCG board account director Britt Sarony added: "We'll be investigating Clinomyn and exploring what space it could move into."
Summer's Eve is an established brand in the US, where it is handled by the Chicago-based Euro RSCG Tatham Partners.