Police are appealing for public assistance to help locate a missing teenager who was last seen in Sydney's north.

Trystien Caceres, 19, was last seen at a home on Ryries Parade, Cremorne, on Wednesday evening. Police were alerted to his disappearance on Thursday.

Police and family members hold concerns for his welfare.

Police have described Mr Caceres as being of Caucasian appearance, with a medium build, approximately 180-185 centimetres tall, with brown hair and brown eyes.

Anyone with information about Mr Caceres is urged to contact police immediately.