A deal has been agreed for Viktor Fischer to join FSV Mainz in the Bundesliga.
The Danish international winger, who arrived on Teesside from Ajax last summer, will leave for an undisclosed fee.
After making his Boro debut against Fulham in the EFL Cup last August, Fischer made a total of 16 Boro appearances last season but missed much of the campaign with a troublesome knee injury.
The last of those appearances was our final home game of the campaign against Southampton. Fischer would provide an assist - one of three during his short Boro stint - as Patrick Bamford scored his first goal since returning to Boro.
Fischer's exit follows that of Julien de Sart, who made a loan move to his native Belgium earlier in the week.