Sharing of pornographic images via email has led to the dismissal of seven workers at the Tees, Esk and Wear Valleys NHS Foundation Trust.
An inquiry had been instituted against 98 employees at various hospitals, but mainly centered around the Hutton Centre at St Luke's Hospital in Middlesbrough.
"We do not tolerate this type of misconduct and the scale of our investigation reflects the seriousness of the issue," said Les Morgan, chief operating officer. "Not everyone who has been investigated has acted improperly but where staff have contravened trust policy we are taking appropriate disciplinary action."
Overall four workers have received written warnings, five are still under investigation and 13 have been let off.