Police with the assistance of Air Wing and SES are searching for 89-year-old Helen Marshall who went missing in Taradale yesterday.
It is believed Helen took her dog for a walk in the Taradale area about 4pm on 17 September.
She was last seen in Old Drummond Road about 5.45pm and her dog was located near Deardon Track in Taradale about 10.30pm.
Police have concerns for her welfare due to her age and as she has a medical condition which can cause her to become disoriented.
Helen is Caucasian in appearance and described as approximately 160cm tall with a medium build and short white hair. She was last seen wearing dark tracksuit pants and a multi-coloured jacket which was mainly purple in colour.
She is known to frequent the Taradale area.
Police have also released an image of Helen in the hope someone recognises her and can provide information regarding her current whereabouts.
Anyone with information about Helen is asked to contact Castlemaine Police Station on 03 5470 4100.