At 4.23am this morning (Saturday), emergency services were called to reports that a man was seriously injured on South Parade in Doncaster city centre.
A post-mortem is due to take place later today and a police cordon in place at the scene.
The public are being asked to avoid the area while police carry out their investigations.
Anyone with information is asked to call 101 quoting incident number 175 of 2 July. Alternatively, anonymous contact the independent charity Crimestoppers via their website Crimestoppers-uk.org or by calling their UK Contact Centre on 0800 555 111.