Police are appealing for public assistance to help locate missing Redan children Shaniqua and Xavier Redmond, Victoria Police say.
The siblings are believed to have left a Bell Street residence overnight, sometime between midnight and 4am.
Police and family members hold concerns for their welfare due to their age.
Shaniqua is 14 years old and is known to frequent the Bridge Mall and Ballarat CBD.
She was possibly wearing a tie-dye shirt with the letters “LSD” on the front, blue track pants and a black-and-white Nike jacket.
Xavier is 10 years old and may have been wearing a grey jumper and navy blue pants.
Investigators believe there is a possibility the pair may be travelling interstate to see a family member in Elizabeth, South Australia.
Police have released images of the siblings in the hope someone recognises them and can provide information on their whereabouts.
Anyone who sights the pair or has information is urged to contact Ballarat Police Station on 5336 6000.