A nude photo of a teacher who works at a state high school in Melbourne's north-east was sent to a year 12 student.
The Victorian Education Department is investigating the incident, and believes that the teacher was not responsible for sending the explicit photo to the student.
It is believed that the teacher sent the image to another adult, and it was sent to the student via an intermediary.
The teacher has not been disciplined, but has been briefed about professional conduct.
"We are investigating how students at the school have obtained this picture," a department spokesman said.
"We are confident that a staff member did not send the picture to any students at the school."
The department has not contacted Victoria Police.