A 30-year-old man needed emergency surgery for serious facial injuries after being stabbed in Harehills.
The man is believed to have been driven in a private vehicle to hospital after the incident around 7pm on Cowper Road.
His injuries are not described as life threatening.
Leeds District, Detective Inspector James Entwhistle said: “The full circumstances of this incident continue to be investigated and we are making further enquiries at the scene today to establish exactly what has occurred."
Det Insp asked any witnesses to contact the police.
Police patrols are being stepped up in the area.