Colchester Hospital University NHS Foundation Trust must tackle concerns over the quality and safety of patient care, the health service regulator has said.
Monitor said the trust was put in special measures "to ensure all its patients receive good quality care".
A formal investigation found the trust had breached its licence to provide health services.
The trust will be required to "put right the patient quality, safety and governance concerns highlighted by the CQC" under the measures, Monitor said.
The hospital will also be matched with a high-performing trust which can offer support and expertise, and an improvement director will also be appointed to ensure their are effective changes.