Wasps have signed flankers Matt Everard and James Harris, while Argentina international Genaro Fessia has been handed a trial at Adams Park.
Everard, 20, arrives from Leicester, where he spent the last four years, and 24-year-old Welshman Harris leaves Newport Gwent Dragons.
Flanker Fessia, 30, last represented his country in November last year.
"Back row is an area we needed to strengthen," Wasps director of rugby Dai Young told the club website.
"We've had some injuries there which means we are lighter there than we'd like.
"We've brought in two young flankers who have plenty of potential and Genaro's international experience will certainly help provide much stronger depth to our back row."