The actress, who was announced as a new regular last November, will depart the medical drama in April or May next year, The Mirror reports.
It is thought that Rouass has told friends that she wants a fresh challenge following her stint playing surgeon Sahira.
A BBC spokesperson confirmed that Rouass is leaving "by mutual consent" to pursue new projects.
Meanwhile, a Holby City insider told the newspaper: "She has proved popular so it was a surprise when we heard she'd be leaving. But we still have time to devise an exit."
Sahira's first Holby City episode aired in February.
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