A 36-year-old man was stabbed in the chest and leg after leaving The Black Cap, a gay pub in Camden in north London.
The attacker, who was part of a group of four men aged about 20 to 25, approached the man in the street and asked if he was gay. The victim ignored him and the attacker walked a little way down the street, before returning to stab him.
The victim is currently recovering in a hospital in central London.
The attack happened at 2.15am on Monday morning. Police are appealing for witnesses. If you were in the area and believe you may have seen the attack, please call Camden police on 020 8733 6474 or contact Crimestoppers anonymously on 0800 555 111.