Gillespie, who is in his third year with the south coast club, is to take up a new role in South Australia
Jason Gillespie will leave Sussex at the end of the 2020 county season.
Head coach Gillespie, who is in his third year with the south coast club, is to take up a new role in South Australia.
The former Australia international already holds the top coaching position at Adelaide Strikers in the Big Bash.
Sussex chief executive Rob Andrew said: “We are very sorry to see Jason leave after three years at the club, but fully understand and support his decision to return home to a new role in South Australian cricket.
“He will stay in Hove to see out our season and continue the great work with the development of our young and exciting team.
“We will have the chance to say thank you and wish him well in the next stage of his coaching career. We will not be making any decision on a replacement for Jason until 2021.”
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