The Care Quality Commission (CQC) made a number of recommendations including ensuring nursing staffing levels were safe at Sandwell General Hospital and City Hospital in Birmingham.
It also called for improvements in A&E, medical care and surgery.
Sandwell and West Birmingham Hospitals NHS Trust said it is "working hard already to address the issues".
Care at the trust was given an overall rating of "requires improvement".
The CQC said: "The trust was rated as 'inadequate' with regard to whether [it] was always providing a service that is safe."
Source: CQC inspection between 14-17 and 25-30 October
The trust said the report made for  "difficult reading".
Chief executive Toby Lewis said: "The areas of improvement identified in the report are not a surprise to us at the trust, even where they are disappointing, or make difficult reading."
CQC's chief inspector, Prof Sir Mike Richards, said: "While we witnessed areas of good practice it is clear that the trust has work to do to make improvements which are sustainable long term."
Inspectors will return to check whether the necessary changes have taken place and the CQC will continue to monitor the trust "closely".
Mr Lewis said: "During the CQC visit, inspectors saw some individual examples of poor practice in some departments around hand washing, security of medicines and completion of patient records."
He said these individual examples "are not acceptable" and it is up to the trust leadership to ensure it gets "the basics right, first time, every time for every patient".

Police hope the scheme will help reduce financial crime by spotting scams before money has been handed over.
The plan is to train every single front-facing employee of banks, building societies and Post Offices.
Cash payments to fraudsters are typically much harder to trace than online payments with the vast majority of cases going unsolved.
Typical frauds of this kind include paying rogue builders, romance scams and elderly abuse.
'It just didn't add up'
Staff at one bank which has trialled the scheme helped stop a customer being swindled out of £13,000.
Ray, who is in his 60s, was approached by a builder at his home in London about some work on his house.
He had withdrawn £6,000 from his local branch after explaining to staff what it was going to be used for.
But when he returned a week later to take out another £13,000 he was recognised by staff member Ann-Marie.
She asked him questions about his cash withdrawal which raised suspicions.
Ray handed over the flier he had been given with the builder's contact details and staff gave him a call.
Ann-Marie added: "The person that answered wasn't very professional and the alarm bells started to ring. Plus the amount he [Ray] wanted to cash and the work he needed done just didn't add up."
Staff contacted the police who visited Ray the next day when the builder was at his property.
Officers did a background check on the builder and which uncovered suspicious activity and he was arrested.
The new scheme, known as the Banking Protocol, is aimed at ensuring banks and police are more active in protecting customers.
It is being run as a joint venture between the police, Financial Fraud Action - which represents banks - and Trading Standards.
All customer-facing bank staff will be told to look out for specific signs that a client may be the victim of ongoing fraud.
If they have suspicions, they are encouraged to call the police and give a special password.
Police trained under the protocol will also commit to investigating the fraud as a priority - often visiting the bank branch, or the customer's home, immediately.
In some cases, they may be able to catch the criminal waiting outside the bank or the victim's home to collect the cash.
Bank staff taking part in the trial scheme in London made 178 calls to police which resulted in 16 arrests.
Banks say £1.4m has already been stopped from leaving customer accounts.
Police, Financial Fraud Action and Trading Standards have hailed the trial a success.
The scheme is expected to begin in the next few weeks with the first 16 police forces trained by the end of June.
The safety of services at a trust running two hospitals has been rated "inadequate" by a health watchdog.
[NEXT_CONCEPT]
All bank staff are to be trained to spot signs that a customer may be withdrawing cash to give to a scammer.