Watch ITV News Central reporter Chris Halpin's full report below
West Midlands Police is failing to record thousands of alleged offences including reports of rape, a highly critical report has found.
Inspectors warned victims could be at more risk of harm because of shortcomings by the force.
An assessment by HM Inspectorate of Constabulary and Fire & Rescue Services (HMICFRS) found 83.8% of reported offences were recorded.
This means at least 38,800 reports of crime each year are not.
The crimes that go unrecorded included sexual offences, domestic abuse and rape.
It highlighted the recording rate for violent crime, which was 77.9%, as a particular cause of concern, adding: "This means that on too many occasions, the force is failing victims of crime."
HM Inspector of Constabulary Wendy Williams said: "I am very disappointed with the result of our recent inspection into how West Midlands Police records crime.
"Not only does this mean the force cannot fully understand the demand it faces to plan accordingly, but it also means that victims could potentially be at more risk of harm, without the required support.
She said the force also needs to improve how it manages domestic abuse cases.
HMICFRS noted improvements since 2014 but rated the force as inadequate for effectiveness at recording reported crime.
West Midlands deputy chief constable Louisa Rolfe said: "While we broadly accept the data underpinning the report, it is certainly not accurate to claim 38,000 crimes have occurred and not been recorded.
"A significant number of these incidents were recorded on our systems but just not classified correctly."
West Midlands Police & Crime Commissioner David Jamieson, added "I have asked the force to make rapid improvements, ensuring that safeguarding is as robust as possible."