Al Ittihad have appointed Argentinian Enzo Trossero as manager until the end of the season.
The 56-year-old had previously coached Saudi League rivals Al Shabab for two years before leaving in 2009 due to family commitments and will replace compatriot Gabriel Calderon, who was sacked last month.
"I accepted the offer to coach Al Ittihad because I'm confident that I'll be coaching a big club and a lot of important stars of Saudi football," said Trossero.
"The period that the club is going through is natural and I hope that I can lead the team to success in the next period.
"I'm confident that Al Ittihad will return stronger than before and hopefully we can compete in the remaining local competitions and in the forthcoming Asian Champions League."