A man was found with facial injuries in a car park in Anne Street, Corby.
The 45-year-old man was assaulted at some point between 8pm and 9pm on Thursday and had his mobile phone, medication, bank card and cash stolen during the incident.
The victim had been visiting a friend in Argyll Street, and it is not known where the assault took place.
He was taken to Kettering General Hospital with facial injuries and police want to speak to anyone who may have seen an assault on the evening of Thursday, January 21, in the Anne Street or Argyll Street areas.
Witnesses or anyone who may have any information about the incident can contact police on 101 or Crimestoppers anonymously on 0800 555111.