The 26-year-old man was on the packed dance floor of Viva, in Mile End Road in South Shields at 2.01am, when he was approached from behind by a man who slashed him across the neck and then made off.
The victim was taken to hospital, where he is detained with 'non life-threatening injuries' and his condition is described as stable. It is believed the injured man and his assailant are known to each other.
The offender is described as a man in his mid 20s, six feet tall and wearing dark clothing.
Anyone with information about this incident should contact police on 101, quoting log number 182 of 18/12/16 or ring the independent charity Crimestoppers on 0800 555 111.