Police are appealing for public assistance to help locate Erinette Walls and her four children.
The family were last known to be residing at an apartment complex in East Melbourne and are believed to have checked out on 10 June.
Erinette, who is 37, is believed to be travelling with her children, 15-year-old Lachlan Kingsley, 13-year-old Georgia Kingsley, 12-year-old Charlie Kingsley and 9-year-old Hudson Kingsley.
Police have concerns as their disappearance is out of character and one of the children requires regular medical treatment.
Investigators believe the group may be travelling in a 2004 silver Toyota Camry with registration UVK-253.
Images of the family have been released in the hope someone can provide information on their current whereabouts.
Anyone who has seen the family or with information on their current whereabouts is urged to call Melbourne West Police on 8690 4444.