The Heart of England NHS Foundation Trust was criticised for overcrowding at the A&E departments of Birmingham Heartlands Hospital and Good Hope Hospital in Sutton Coldfield.
Issues with infection control at both sites were also identified in the Care Quality Commission (CQC) report.
The trust said it had already addressed some issues.
The inspection, between 8 and 11 December, looked at departments at Good Hope Hospital, Birmingham Heartlands Hospital and Solihull Hospital. It said overcrowding was creating a “high stress, high risk” environment.
The “requires improvement” rating mirrors the rating given by inspectors following a previous inspection in 2013.
CQC’s Chief Inspector of Hospitals, professor Sir Mike Richards, said, “While there were some areas of good practice, it was clear that significant work was still needed to improve services so that they meet the standards people have a right to expect.”
The former Chief Executive of the trust, Dr Mark Newbold, stepped down last year after criticism by the watchdog Monitor.
Heart of England NHS Foundation Trust Chief Executive Andrew Foster said it was working with the CQC and Monitor to develop an improvement plan.
Mr Foster said, “We have accepted the CQC report in full and agreed to implement all of its recommendations. We know that these actions will help the trust function more effectively for patients and be a better place for our staff to work in.”