A 53-year-old man has been arrested on suspicion of murder in Barry.
South Wales Police attended a property on West Walk at around 1am on Friday morning and found a man who was pronounced dead at the scene.
The man has not yet been named.
Officers are appealing for any information that could help their investigations.
Senior Investigating Officer DS Darren George said: "I can confirm a murder investigation has commenced following the discovery of the body of a local man during the early hours of this morning at West Walk in Barry.
"There will be a considerable police presence in the area over the coming days as the investigation continues. The victim has yet to be formally identified.
"This a direct appeal to the local community who may be able offer information in relation to any suspicious activity in and around the West Walk area of Barry, particularly between the evening of Monday August 30th and the early of hours of this morning (Friday September 3rd), no matter how insignificant you believe any information may be, please contact the major incident room."