Teen boy missing in Brisbane

A 16-year-old boy with a medical condition is missing in Brisbane.

Police say Christopher Flenady hasn't been seen since 4.20pm on Saturday when he was at a Gildor St address in Boondall in north Brisbane.

He hasn't made contact with his family.

Police say they are worried about him because the behaviour is out of character and he has an unspecified medical condition.

He is Caucasian, about 170cm tall with a slim build, brown hair and brown eyes. He was wearing dark blue tracksuit pants and jumper, orange and white running shoes and a Parramatta Eels cap.