Two men were reportedly fighting on the 127 bus on Loughborough Road.
Around 5.30pm on Wednesday 9 June a man was left with injuries to his nose and teeth after he was allegedly assaulted by another man on the 127 bus that was parked outside a pub on Loughborough Road.
The man lost a tooth and was taken to Leicester Royal Infirmary.
Police said the suspect is white, aged around 25 and 5'7" tall with a slim build and a mousey-brown “curtain” haircut.
PC Chris Hughes said: “We are carrying out investigations to try and identify the man who reportedly carried out this assault.
“We would like to hear from anyone who was travelling on the 127 bus and may have seen or heard an argument.”
Anyone with any information is asked to call 101 quoting reference 21*318606.