Edinburgh have signed Fiji Sevens duo Eroni Sau and Kalione Nasoko, along with hooker Mike Willemse and back-row Nick Haining.
The quartet will arrive on two-year contracts for the start of next season in the Pro14.
Nasoko is the current Fiji Sevens captain, while Sau has one full international cap.
Willemse is joining from league rivals Southern Kings in his native South Africa and Haining is with Bristol.
"Mike has a lot of experience in Super Rugby," head coach Richard Cockerill said. "He's a very competent hooker that plays in the style of Stuart Mclnally.
"He's all-action, very good over the ball and extremely dynamic. He will push everybody to the next level."
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Willemse, 26, who played for South Africa at Under-20 level, joined Southern Kings in 2017 and has made 36 appearances for the Port Elizabeth outfit, scoring five tries.
Back-row Haining, 28, moved to Bristol in summer 2017 from Jersey Reds and has one try from his seven Premiership matches this season.
"Nick is someone I've been looking at for a while," Cockerill added. "He's Australian, but Scottish qualified. He's a very good player and keen to try to push himself into the national squad."
Sau, nicknamed "Sledgehammer", enjoyed an impressive Test debut for Fiji in November, scoring a hat-trick in a 68-7 victory over Uruguay.
The 29-year-old is currently with French Top 14 club Perpignan and Cockerill said: ""Anyone who has watched sevens will know Eroni Sau. He's a very strong and powerful runner, he's tough and very combative.
"A nickname like 'The Sledgehammer" gives you an idea of what he does with and without the ball,"
Cockerill described Kalione as "a tremendously exciting player", with the 28-year-old a winger with experience at outside centre.
"Kalione brings something different to our back-three," he added. "He gives us a little bit more of an x-factor and, as you see with the good teams around Europe, you need that type of threat."